Description
Title of Invention
COMMUNICATION CONTROL APPARATUS, COMMUNICATION CONTROL
5 METHOD, RADIO COMMUNICATION APPARATUS, RADIO
COMMUNICATION METHOD AND RADIO COMMUNICATION SYSTEM
Technical Field
[OOOl]
10 The present disclosure relates to a communication control apparatus, a
communication control method, a radio communication apparatus, a radio
con~municationm ethod and a radio communication system.
Background Art
15 [0002]
A traffic amount handled in radio communication service has increased
rapidly in recent years. In the fourth generation cellular communication service
which is scheduled to he in practical use around 2015, it is expected that a data rate
of 1 Gbps at a maximum in a semi-fixed environment and 100 Mhps at a maximum
20 in a mobile environment can be achieved. However, because development of a
cellular communication system does not catch up with increase of traff~c,t here still
remains a risk of local degradation of a data rate due to increase of system load and
occurrence of a network failure. Non-Patent Literature 1 proposes active utilization
of a small cell as one of measures against such a risk.
25 [0003]
Macro cells which have a relatively large cell size, are disposed adjacent to
each other so as to cover a broad geographical area. On the other hand, small cells
cover only a relatively narrow area independently. The small cells can be used to
complement radio communication service of the macro cells or provide specific
30 service.
[0004]
When the number of active small cells operating within a service area of the
macro cells increases, more radio signals from cells in the vicinity interfere with a
radio signal of one cell. Therefore, for example, in a situation where terminal
density is low and gain as an effect of offload of traffic is small, increase of active
5 small cells ends up degrading of throughput as the whole system. Non-Patent
Literature 2 discloses a simulation result regarding relationship between a ratio of
small cells which are activated (turned on) and capacity gain.
Citation List
10 Non-Patent Literature
[OOOS]
Nan-Patent Literature 1: NTT DOCOMO, "Text Proposal for TR36.923 on
Small Cell Enhancement Scenarios", 3GPP TSG RAN WGl Meeting #72, January
28 to February 1,2013, R1-130748
15 Non-Patent Literature 2: LG Electronics, "Analysis and design
considerations of cell ordoff in small cell", 3GPP TSG RAN WGl Meeting #73,
Fukuoka, Japan, May 20-24,2013, R1-132236
Summary of Invention
20 Technical Problem
[0006]
As disclosed in Non-Patent Literature 2, it may be beneficial to
activateldeactivate (onlofq small cells, that is, dynamically control operation modes
in terms of optimization of system capacity. However, increase of signaling
25 associated with control of the operation modes of the small cells can cause a new
problem of increase of signaling ovcrhead.
[0007]
Accordingly, it is desirable to provide a mechanism which enables efficient
signaling to control the operation modes of the small cells.
30
Solution to Problem
[OOOS]
According to the present disclosure, there is provided a co~nmunication
control apparatus including: a conlmunication unit configured to communicate with
each of communication nodes operating a plurality of sinall cells, each of which
5 belongs to at least one of a plurality of small cell groups; a determining unit
configured to determine whether operation modes of the plurality of small cells
sllould be set to be an active mode in units of the small cell groups; and a signaling
unit configured to signal a control message for specifying the operation modes in
units of the small cell groups, determined by the determining unit to the
10 communication nodes via the comn~unicationu nit.
[OOO9]
According to the present disclosure, there is provided a communication
control method including: grouping a plurality of small cells in a manner that each
small cell belongs to at least one of a plurality of small cell groups in a
15 communication control apparatus which communicates with each of communication
nodes operating the plurality of small cells; determining whether operation nlodcs of
the plurality of small cells should be set to be an active mode in units of the small
cell groups; and signaling a control message for specifying the determined operation
modes in units of the small cell groups to the communication nodes.
20 [OOlO]
According to the present disclosure, there is provided a radio
communication apparatus including: a radio communication unit configured to
operate a first small cell among a plurality of small cells, each of which belongs to at
least one of a plurality of small cell groups; and a control unit configured to set an
25 operation mode of the first small cell according to a control message for specifying
an operation mode determined for the small cell group to which the first small cell
belongs, the control message being signaled from a control node which determines
whether operation modes of the plurality of small cells should be set to be an activc
mode in units of the small ccll groups.
30 [OOll]
According to the present disclosure, there is provided a radio
communication method including: in a radio comlnunication apparatus which
operates a first small cell among a plurality of small cells, each of which belongs to
at least one of a plurality of small cell groups, receiving a control message for
specifying an operation mode determined for a small cell group to which the first
5 small cell belongs, the control message being signaled fiom a control node which
determines whether operation modes of the plurality of small cells should be set to be
an active mode in units of the small cell groups; and setting the operation mode of
the first small cell according to the received control message.
[0012]
10 According to the present disclosure, there is provided a radio
comlnunication system including: a communication conwol apparatus which includes
a plurality of communication nodes configured to operates a plurality of small cells,
each of which belongs to at least one of a plurality of small cell groups, a
determining unit configured to determine whether operation modes of the plurality of
15 small cells should be set to be an active mode in units of the small cell groups, and a
signaling unit coniigured to signal a control message for specifying the operation
modes in units of the small cell groups, determined by the determining unit to the
plurality of communication nodes.
20 Advantageous Effects of Invention
[0013]
According to the technique according to the present disclosure, it is possible
to efficiently perform signaling to control operation modes of small cells.
Note that the effects described above are not necessarily limited, and along
25 with or instead of the effects, any effect that is desired to be introduced in the present
specification or other effects that can be expected from the present specification may
be exhibited.
Brief Description of Drawings
30 [0014]
[FIG. I] FIG. 1 is a &st explanatory diagram for explaining outline of a radio
co~llmunications ystem to wluch a technique according to the present disclosure is to
be applied.
[FIG. 21 FIG. 2 is a second explanatory diagram for explaining outline of a radio
communication system to which a technique according to the present disclosure is to
5 be applied.
[FIG. 3A] FIG. 3A is an explanatory diagram illustrating a first example of sector
division of a macro cell.
[FIG. 3B] FIG. 3B is an explanatory diagram illustrating a second example of sector
division of a macro cell.
10 [FIG. 41 FIG. 4 is an explanatory diagram illustrating some examples of arrangement
of control entities.
[FIG. 51 FIG. 5 is a block diagram illustrating one example of a configuration of a
communication control apparatus according to one embodiment.
[FIG. 61 FIG. 6 is an explanatory diagram for explaining a first configuration example
15 of small cell groups.
[FIG. 7A] FIG. 7A is a first explanatory diagram for explaining activation of small
cells in units of the small cell groups in the first configuration example.
[FIG. 7B] FIG. 7B is a second explanatory diagram for explaining activation of small
cells in units of the small cell groups in the first configuration example.
20 [FIG. 81 FIG. 8 is an explanatory diagram for explaining a second configuration
example of the small ccll groups.
[FIG. 9A] FIG. 9A is a first explanatory diagram for explaining activation of small
cells in units of the small cell groups in the second configuration example.
[FIG. 9B] FIG. 9B is a second explanatory diagram for explaining activation of small
25 cells in units of the small cell groups in the second configuration example.
[FIG. 101 FIG 10 is an explanatory diagram for explaining control of operation
modes for each sector.
[FIG. 11A] FIG. 11A is an explanatory diagram illustrating one example of a control
message corresponding to the first configuration example of the small cell groups.
30 [FIG. 11 B] FIG. 11B is an explanatory diagram illustrating one example of a control
message corresponding to the second cor~figuratione xample of the small cell groups.
[FIG. 121 FIG. 12 is an explanatory diagram illustrating one example of a
configuration of small cell data.
[FIG. 131 FIG. 13 is an explanatory diagram illustrating one example of a
configuration of an operation mode table.
5 [FIG. 141 FIG. 14 is a sequence diagram illustrating one example of flow of
communication control processing according to one embodiment.
[FIG. 15A] FIG. 15A is a flowchart illustrating a first example of flow of operation
mode determination processing illustrated in FIG. 14.
[FIG. 15B] FIG. 15B is a flowchart illustrating a second example of flow of operation
10 mode determination processing illustrated in FIG. 14.
[FIG 15C] FIG. 15C is a flowchart illustrating a third example of flow of operation
mode determination processing illustrated in FIG. 14.
[FIG 15D] FIG. 15D is a flowchart illustrating a fourth example of flow of operation
mode determination processing illustrated in FIG. 14.
15 [FIG. 15E] FIG. 15E is a flowchart illustrating a fifth example of flow of operation
mode determination processing illustrated in FIG. 14.
[FIG. 161 FIG. 16 is a block diagram illustrating one example of a configuration of a
radio communication apparatus according to one embodiment.
[FIG. 17A] FIG. 17A is a flowchart illustrating a first example of flow of operation
20 mode setting processing.
[FIG. 17B] FIG. 17B is a flowchart illustrating a second example of the flow of the
operation mode setting processing.
[FIG. 181 FIG. 18 is an explanatory diagram for explaining a hierarchical role model
in a spectrum access system (SAS).
25 [FIG. 191 FIG. 19 is a block diagram illustrating one example of a schematic
configuration of a management server.
[FIG. 201 FIG. 20 is a block diagram illustrating a first example of a schematic
configuration of an eNB.
[FIG. 211 FIG. 21 is a block diagram illustrating a second example of a schematic
30 configuration of an eNB.
[FIG. 221 FIG. 22 is a block diagram illustrating an example of a schematic
configuration of a smartphone.
[FIG. 231 FIG. 23 is a bloclc diagram illustrating an example of a schematic
configuration of a car navigation apparatus.
Description of Embodiments
[OOlS]
Hereinafter, a prefe~sed embodiment of the present disclosure will be
described in detail with reference to the appended drawings. In this specification
and the drawings, elements that have substantially the same function and structure
10 are denoted with the same reference signs, and repeated explanation is omitted.
[0016]
Further, the description will be provided in the following order.
1. Outline of System
2. Configuration Example of Communication Control Apparatus
2-1. Configuration of Each Unit
2-2. Configuration of Small Cell Group
2-3. Control Message
2-4. Data Configuration
2-5. Processing Flow
3. Configuration Example of Radio Communication Apparatus
3-1. Configuration of Each Unit
3-2. Processing Flow
4. Application to Spectrum Access System (SAS)
5. Application Example
25 6. Conclusion
[0017]
4 . Outline of System>
FIG. 1 and FIG. 2 are explanatory diagrams for explaining an outline of a
radio comn~unication system 1 to which a technique according to the present
30 disclosure is to be applied. Referring to FIG. 1, the radio co~n~nunicatiosnys tem 1
includes a macro cell base station 10, a plurality of small cell base stations, and a
plurality of terminal apparatuses.
[0018]
The macro cell base station 10 is a base station which provides first radio
communication service within a macro cell 12. The macro cell base station 10 can
5 operate the macro cell 12, for example, by being legally approved, or by utilizing a
frequency channel for which right of use or right of preferential use is provided.
The macro cell base station 10 may operate the macro cell 12 using a frequency
division duplex (FDD) scheme, or may operate the macro cell 12 using a time
division duplex (TDD) scheme. The terminal apparatuses located within the macro
10 cell 12 can be connected to the macro cell base station 10. In the example of FIG.
lA, a plurality of terminal apparatuses including a terminal apparatus 30a are
connected to the macro cell base station 10. A terminal apparatus connected to the
macro cell base station will be also referred to as a macro cell telminal.
[0019]
15 Small cell base stations 20a and 20b x e base stations which respectively
provide second radio communicatio~l service within the macro cell 12. In the
present specification, the small cell is concept including a femto cell, a nano cell, a
pic0 cell, a micro cell and a relay cell. The second radio communication service
may be radio communication service substantially equivalent to the first radio
20 communication service, which increases capacity of the first radio communication
service, for exan~ple, at a hot spot. Alternatively, the second radio communication
service may be radio communication service different from the first radio
communication service (for example, in terms of a frequency band being used, a
radio access technique or a service provider). The second radio cornmunicatioll
25 service may be provided by secondarily utilizing a frequency channel for the first
radio communication service.
[0020]
In one embodiment, tlie small cell base station can operate in at least two
operation modes of an active mode and a standby mode. In the present
30 specification, the active mode refers to a mode in which the small cell base station
transmits various signals required for the terminal to be connected to the small ccll.
The signal required for the terminal to be comlected to the small cell call include, for
example, a reference signal (also referred to as a beacon signal, a pilot signal or a
synchronization signal) on downlink and other control signals. In the active mode,
power and clock arc continuously supplied to a radio cornmullication circuit and a
5 control circuit of the small cell base station. On the other hand, the standby mode
refers to a mode in which a control signal such as a reference signal is not
transmitted (or at least, transmission ficquency of the control signal is suppressed).
In the standby mode, power and clock are, for example, intermittently supplied or not
supplied to the radio con~n~unicatiocnir cuit of the small cell base station. The
10 concept of the standby mode can include an inactive mode, an idle mode, a sleep
mode and a dom~ant mode. In the standby mode, any part of a radio frequency
(RF) unit or a digital unit or both of them of the radio communication circuit may be
turned off. It should be noted that the small cell base station may further be able to
operate in an operation mode different from the active mode and the standby mode.
15 [0021]
In the example of FIG. 1, the small cell base stations 20a and 20b operate in
the standby mode. The small cell base station 20a does not transmit a reference
signal for the small cell 22a. Therefore, a terminal apparatus 30b located in the
vicinity of the small cell base station 20a is connected to the macro cell base station
20 10 instead of being connected to the snlall cell base station 20a. On the other hand,
in the example of FIG. 2, a plurality of small cell base stations including the small
cell base stations 20a and 20b operate in the active mode. The small cell base
station 20a transmits a reference signal for the small cell 22a on downlink. The
small cell base station 20b transmits a reference signal for the small cell 22b on
25 downlink. The ternlinal apparatus 30b located in the vicinity of the small cell base
station 20a is connected to the small cell base station 20a. A terminal apparatus
connected to the small cell base station will be also referred to as a small cell
terminal.
roo221
30 It should be notcd that in the present specification, when it is not nccessary
to distinguish between the small cell base stations 20a and 20b, by abbreviating an
alphabetical character at the tail end of the reference numeral, these are collectively
referred to as a small cell base station 20. The same will also apply to other
components such as the small cells 22a and 22b (small cell 22) and terminal
apparatuses 30a and 30b (terminal apparatus 30).
5 [0023]
The small cell base station 20 is connected to the macro cell base station 10
via a back haul link. The back haul link may be a wired link or a radio link. The
macro cell base station 10 is connected to a core network 5. The core network 5
includes a plurality of upper nodes which respectively have roles such as
10 management of user information, management of mobility of terminals, transferring
of packets and a role as a gateway, or the like. The small cell base station 20 may
be also connected to the core network 5. It should be noted that the small cell base
station 20 may be connected to the core network 5 and the macro cell base station 10
via a packet data network (PDN) 7. The PDN 7 includes, for example, Internet.
15 [0024]
As in the example of FIG. 1, when most of the small cell base stations 20
located within the macro cell 12 are set to operate in the standby mode, signals are
not transmitted from these small cell base stations 20 on downlink (access link with
small cell terminals). In this case, interference with a desired signal transmitted and
20 received between the macro cell base station 10 and the macro cell terminal is
reduced. Particularly, in a situation where there is a small traffic amount occurring
in the macro cell 12 or terminal density is low, it is more beneficial to obtain capacity
gain by reducing interference than to distribute traffic by utilizing small cells. On
the other hand, in a situation where terminal density increases and a large traffic
25 amount occurs as in the example of FIG. 2, it is possible to optimize system capacity
by activating some small cells and distributing (off-loading) load of traffic among the
macro cell and active small cells.
[0025]
However, while FIG. 1 and FIG. 2 merely illustrate a small number of small
30 cells for the purpose of simplicity, the number of small cell base stations deployed in
the macro cell in an actual envirollment can reach several tens to several hundreds.
Accordingly, if individual signaling is fiequently exchanged between control entities
and the small cell base stations to dynanlically control the operation modes of the
small cells, a significant amount of signaling overhead will occur. Therefore, in the
technique according to the present disclosure, by grouping a plurality of small cells
5 into small cell groups and introducing control entities which control the operation
modes in units of the small cell groups, increase of signaling associated with
dynamic control of the operation modes is suppressed.
[0026]
The control entities group a plurality of small cells disposed in a given
10 management area into small cell groups. The small cells may be grouped using any
standard. Howevel; while in a clustering technique disclosed in Non-Patent
Literature 1, a group of small cells which are disposed geographically close to each
other form one small cell cluster, in the technique according to the present disclosure,
each small cell group includes a plurality of small cells disposed in a distributed
15 manner over the management area. By this means, it is easy to adjust a ratio of
active small cells according to a traffic state within the management area. Some
examples of the configuration of the small cell groups will be described further later.
[0027]
In one example, the management area can correspond to a macro cell. In
20 this case, the control entities determine small cell groups for which the operation
modes of the small cells should be activated for each macro cell. In other examples,
the management area can correspond to each sector of the macro cell. In this case,
the control entities determine small cell groups for which the operation modes of the
small cells should be activated for each sector. While an effect of reduction of
25 signaling overhead increases when the management area is larger, finer control can
be performed on the operation mode when the management area is smaller.
Referring to FIG. 3A, the macro cell 12 includes six sectors 14a to 14f divided into
equal pats in an azimuth angle. The management area may he equal to the macro
cell 12 or may be equal to each of the sectors 14a to 14f. The macro cell may be
30 divided into sectors in a three dimensional manner. Referring to FIG. 3B, the macro
cell 12 includes three sectors 15a to 15c divided in an elevation/depression angle.
The sector 15a covcrs the vicinity of the ground, the sector 15b covers lower floors
of a building 9, and the sector 15c cover higher floors of the building 9. The
management area may be equal to each of the sectors 15a to 15c.
[0028]
5 The control entities may be implemented on various kinds of nodes relating
to radio communication. FIG. 4 illustrates somc examples of arrangement of the
control entities. As a first example, the control entity 1OOa is disposed at the macro
cell base station 10. As a second example, the control entity lOOb is disposed at the
small cell base station 20. As a third example, the control entity lOOc is disposed at
10 a node within the core network 5. As a foui-th example, the control entity lOOd is
disposed at a node within the PDN 7. In any case, the control entities communicate
with each of the small cell base stations which operate the small cells, and signal the
operation modes determined in units of the small cell groups to the small cell base
stations. An exemplary embodiment for realizing such a mechanism will be
15 described in detail in the following section.
[0029]
<2. Configuration Example of Communication Control Apparatus,
In this section, it is assumed that the control entity is implemented on the
macro cell base station 10. However, this description can be also applied to a case
20 where the control entities are implemented on other kinds of nodes.
[0030]
FIG. 5 is a block diagram illustrating one example of a configuration of the
co~nmunication control apparatus 100 according to one embodiment. The
communication control apparatus 100 corresponds to the macro cell base station 10
25 at which the above-described control entity is implemented. The communication
control apparatus 100 includes a radio communication unit 110, a network
con~mnwlicationu nit 120, a storage unit 130 and a control unit 150.
[003 11
[2-1. Configuration of Each Unit]
30 (1) Radio Communication Unit
The radio communication unit 110 provides first radio communication
service to the terminal apparatuses 30 located within the macro cell 12. For
example, the radio co~nmuuicationu nit 110 transmits a reference signal on downlink.
The reference signal is searched by the terminal apparatuses 30 during procedure of
cell selection or cell reselection. Further, the terminal apparatuses 30 derive
5 co~nmunication quality for each cell which becomes a basis of handover
determination by executing measurement for the refcrence signal. Further, the radio
communication unit 110 transmits system information on a downlink broadcast
channel. The system information on the broadcast channel generally includes static
control information (also referred to as a white list) such as an operation frequency
10 band of the macro cell 12 and the number of antennas of the radio communication
unit 110. Dynamic control information can be eansmitted in a control information
area (for example, a system information block (SIB)) on a shared channel. The
radio communication unit 110 establishes a radio bearer for each of the terminal
apparatuses 30 connected to the macro cell base station 10. The radio hearer
15 receives uplink traffic from the terminal apparatuses 30 on uplink and transmits
downlink traffic to the terminal apparatuses 30 on downlink. Uplink and downlink
data rates can be adjusted according to a quality of service (QoS) class of each
terminal.
[0032]
20 (2) Network Communication Unit
The network communication unit 120 mediates communication between the
macro cell base station 10, and upper nodes within the core network 5, other macro
cell base stations and the small cell base station 20. As one example, when the
macro cell base station 10 operates using an LTE scheme or an LTE-A scheme, the
25 network communication unit 120 establishes communication links called an S1-U
interface and an S1-MME interface respectively with a serving-gateway (S-GW) and
a mobility management entity (MME) within the core network 5. Further, the
network communication unit 120 establishes a communication link called an X2
interface with other macro cell base stations. Still firthel; the network
30 communication unit 120 establishes the above-described back haul link with the
small cell base station 20 operating within the macro cell 12. It should be noted that
a radio link between the radio comm~i~licatiounn it 110 and the small cell base station
20 may be utilized as a radio back haul link.
LO0331
(3) Storage Unit
5 The storage unit 130 stores a program and data for operation of the macro
cell base station 10 using a storage medium such as a hard disk and a semiconductor
memory. The data stored by the storage unit 130 can include, for example, small
cell data 131 which will be described later and an operation mode table 145.
[0034]
10 (4) Control Unit
The control unit 150 controls general operation of the colnmunication
control apparatus 100 using a processor such as a central processing unit (CPU) and
a digital signal processor (DSP). In the present embodiment, the control unit 150
includes a communication control unit 152, a mode determining unit 154 and a
15 signaling unit 156.
[0035]
(4-1) Communication Control Unit
The communication control unit 152 controls provision of the first radio
communication service. For example, the communication control unit 152 makes
20 the network communication unit 120 transfer uplink data traffic received by the radio
communication unit 110 to the core network 5 or other macro cell base stations or the
small cell base station 20 depending on its address. Further, the communication
control unit 152 makes the radio communication unit 110 transmit downlink data
traffic received from other nodes by the network communicatioll unit 120 to the
25 terminal apparatus 30 to which the downlink data traffic is addressed. Further, the
communication control unit 152 makes the radio com~nunication unit 110 receive a
report indicating communication quality of downlink measured by the terminal
apparatus 30 (for example, a measurement report or a channel quality indicator (CQI)
report). Furthel; the comnlunication control unit 152 makes the radio
30 coln~nunicatiou~nl it 110 measure communication quality of uplink.
[0036]
(4-2) Mode Dcternlining Unit
The mode determining unit 154 determines which operation mode should be
set for each of the plurality of small cells 22 disposed within the macro cell 12 in
units of the small cell groups. The mode determining unit 154 may periodically
5 determine the operation modes. Fui-tl~el; the mode determining unit 154 may
execute determination of the operation modes triggered by occurrence of events such
as reception of a determination request from any node, newly registration or
elimination of a small cell and change of a monitored index.
[0037]
10 In the present embodiment, the small cells 22 respectively belong to at least
one of the plurality of small cell groups. The mode deteimining unit 154
determines the operation modes using a determination index relating to system
capacity requirements in units of the small cell groups. As described above,
candidates of the operation modes include at least the active mode and the standby
15 mode. Typically, the mode determining unit 154 determines the operation modes
for each small cell group so as to increase density of active small cells in the
management area when the determination index indicates that larger system capacity
is required. Adversely, the mode determining unit 154 determines the operation
modes for each small cell group so as to reduce density of active small cells in the
20 management area when the determination index indicates that only small system
capacity is required.
[003 81
As one example, the determination index relating to the system capacity
requirements inay include an actual traffic amount actually occurring in the
25 management area. As another example, the determination index relating to the
system capacity requirements may include a predicted traffic amount predicted to
occur in the management area. These traffic amounts can be expressed using, for
example, the number of bits per unit time. For example, the mode determining unit
154 can predict the traffic amouilt based on the QoS classes of the termiilals existing
30 in the managcmc~lt arca. When the actual traffic amount or the predicted traffic
amount is higher, it is desired to secure larger system capacity. Adversely, when the
actual traffic amount or the prcdicted traffic alnount is lower, it is desirable to reduce
interference within the management area by refraining from activating too many
small cells.
[0039]
5 Further, as another exan~ple, the determination index relating to system
capacity requirements may include the number of terminals existing in the
management area. The number of terminals here may be a total number of
terminals or the number of active terminals. To count the number of terminals, the
number of radio bearers at the radio comnlunication unit 110 may be counted.
10 When the counted number of terminals is larger, it is desired to secure larger system
capacity. Adversely, when the number of terminals is smaller, it is desirable to
reduce interference within the management area by refraining from activating too
many small cells.
[0040]
16 The mode determining unit 154 may switch the above-described
determination index to be used for determination of the operation mode according to
terminals handled within the system or types of traffic. For example, a machine
type communication (MTC) terminal which performs machine to machine (M2M)
communication steadily causes a relatively small amount of traffic. Therefore,
20 while, for a normal user terminal, a traffic amount which directly affects load of the
system is suitable as the determination index, for the MTC terminal, it can be said
that it is beneficial to use the number of terminals as the determination index given
easiness of counting. Therefore, the mode determining unit 154 can use the number
of terminals as the determination index when M2M communication or the MTC
25 ternlinal is handled, and, otherwise, can use the (actual or predicted) traffic amount
as the determination index.
[0041]
In one example, the storage unit 130 stores the operation mode table 145
which maps a value of the dete~mination index and the operation mode for each
30 small cell group. The mode determining unit 154 acquires data co~~espondintog
the value of the continuously monitored determination index from the operation
rnode table 145 and determines the operation modes in units of the small cell groups.
According to this configuration, it is possible to promptly determine optimal
operation modes according to the latest state within the management area without
requiring complicated operation. The mode determining unit 154 may switch a
5 table to be used for determination of the operation modes according to temporal
conditions (for example, day of week or a time zone). For example, tendency of a
location where traffic occurs diiTers between weekdays and holidays, or between
daytime and early morninglmidnight. Accordingly, by switching the operation
mode table according to the temporal conditions, it is possible to make the operation
10 modes of the small cells confornl to movement of the user more appropriately.
LO0421
In other examples, the mode determining unit 154 determines an optimal
pattern of the operation mode for each small cell group conforming to the value of
the determination index by sequentially scanning a plurality of patterns and verifying
15 compatibility with the determination index. According to this configuration, it is
possible to dynamically control the operation modes in units of the small cell groups
without storing the above-described operation mode table in advance.
[0043]
It should be noted that there is a case where the small cells are dynamically
20 operated by a mobile terminal operating as the macro cell terminal or the small cell
terminal temporarily executing a base station function. In the present specification,
such a mobile terminal is referred to as a dynamic AP, and the small cell operated by
the dynamic AP is referred to as a dynamic cell. Typically, performance (of a
processor, a memory, a battery, or the like) of the dynamic AP is inferior to that of a
25 fixed base station. Therefore, the mode determining unit 154 may determine to
preferentially set the operation mode of a first small cell group to which the dynamic
cell does not belong to be an active mode over a second small cell group to which the
dynamic cell belongs. For example, a special small cell group including the
dynamic AP (therefore, can be activated only when advanced load distribution is
30 required) may be defined.
LO0441
(4-3) Signaling Unit
The signaling unit 156 executes signaling for controlling the operation
modes of the small cells via the back haul link established bctween the
communication control apparatus 100 and each small cell base station 20. For
5 example, the signaling unit 156 signals an allocation message indicating allocation of
the small cell groups to the small cell base stations 20 which operate the small cells
upon initial registration of each small cell. Further, the signaling unit 156 signals a
control message for specifying the operation modes in units of the small cell groups
determined by the mode determining unit 154 to each small cell base station 20.
10 The control message is typically, broadcasted or multicasted to the plurality of small
cell base stations 20 on the back haul link.
[0045]
In one example, the above-described control message may include a set of
flags indicating the determined operation mode for each small cell group. For
15 example, it is assumed that there are two candidates (an active mode and a standby
mode) for the operation mode, and the total number of small cell groups is M. In
this case, it is possible to specify the determined operation modes for all the small
cells only with a bit sequence of M bits. Alternatively, the above-described control
message may include identification information of the small cell group for which it is
20 determined that the active mode should be set. Some examples of a format of the
control message will be described in detail later.
[0046]
[2-2. Configuration of Small Cell Group]
(1) First Configuration Example
25 FIG. 6 is an explanatory diagram for explaining a first configuration
example of the small cell group. Referring to FIG. 6, a geographical area covered
by the macro cell 12 is divided into a plurality of grid-like segments. Small cells
operated by the small cell base stations (SBS) 20 located in every other selected
segments in a longitude (lateral) direction and in a latitude (longitudinal) direction
30 fonn one small cell group.
LOO471
Here, for convenience of explanation, each segment is expressed with a
segment SG[m, n] using an index m in the longitude direction and an index n in the
latitude direction. For example, the small cell group GI1 includes small cells
operated by the small cell base stations 20 illustrated with hollow upward triangles,
5 located in a segment SG[2i, 2j] (where i, j are arbitrary natural numbers). The small
cell group GI2 includes small cells operated by the small cell base stations 20
illustrated with hollow downward triangles, located in a segment SG[2i-1, 2j-11.
The small cell group G13 includes small cells operated by the small cell base stations
20 illustrated with solid downward triangles, located in a segment SG[2i-1, 2j-11.
10 The small cell group G14 includes small cells operated by the small cell base stations
20 illustrated with solid upward triangles, located in a segment SG[2i, 2j-11. That is,
each of these small cell groups G11, G12, G13 and G14 includes a plurality of small
cells disposed over the macro cell 12 in a distributed manner.
[0048]
15 It should be noted that an example where small cells are uniformly
distributed is described here for simplicity of explanation. However, actually, there
may be a segment where a small cell does not exist. Further, the number of small
cells (density) for each segment may be different, and, for example, more small cells
may be disposed in a segment which is statistically known as a segment where traffic
20 concentrates. Further, the shape and the size of the segment may not be uniform.
LO0491
FIG. 7A and FIG. 7B are explanatory diagrams for explaining activation of
small cells in units of the small cell groups in the first configuration example
illustrated in FIG. 6. In the first configuration example, each small cell belongs to a
25 single small cell group (that is, one of the small cell groups G11, G12, G13 and G14).
The mode determining unit 154 determines that the operation modes of more small
cell groups should be set to be the active mode when the determination index
indicates that larger system capacity is required. For example, in the macro cell 12,
when the determination index relating to the system capacity requirements indicates
30 the lowest value, thc operation modes are set to be the standby mode for all the small
cell groups G11, G12, G13 and G14. When the determination index increases to
some extent, as illustrated with the shaded segment in FIG. 7A, the mode
determining unit 154 activates the small cell group G11. When the determination
index further increases, as illustrated with the shaded segment in FIG. 7B, the mode
determining unit 154 additionally activates the small cell group G12. When the
5 determination index continues to furthcr increase, the mode determining unit 154 can
sequentially and additionally activate the small cell groups G13 and G14.
[0050]
(2) Second Configuration Example
FIG. 8 is an explanatory diagram for explaining a second configuration
10 example of the small cell groups. In the second configuration example, each small
cell belongs to one or more small cell groups and the plurality of small cell groups
include different numbers of small cells. For example, the small cell group G21
includes small cells operated by the small cell base stations 20 illustrated with hollow
upward triangles, located in a segment SG[2i, 2j] (where i, j are arbitrary natural
15 numbers). The small cell group G22 includes small cells operated by the small cell
base stations 20 illustrated with hollow downward triangles, located in a segment
SG[2i-I, 2j-11, in addition to the small cells included in the small cell group G21.
The small cell group G23 includes small cells operated by the small cell base stations
20 illustrated with solid downward triangles, located in a segment SG[2i-1, 2j], in
20 addition to the small cells included in the small cell group G22. The small cell
group G24 includes small cells operated by the small cell base stations 20 illustrated
with solid upward triangles, located in a segment SG[2i, 2j-11, in addition to the
small cells included in the small cell group G23. Also in the second configuration
example, each of the small cell groups G21, G22, G23 and G24 includes a plurality
25 of small cells disposed over the macro cell 12 in a distributed manner. It should be
noted that as with the first configuration example, actually, there may be a segment
where a small cell does not exist. Further, the number of small cells (density) for
each segment may be different.
[0051]
30 FIG. 9A and FIG. 9B are explanatory diagrams for explaining activation of
the snlall cells in units of the small cell groups in the second configuration example
illustrated in FIG. 8. In the second configuration example, the mode deter~nining
unit 154 determines that the operation modes of the small cell groups including more
small cells should be set to an active nlode when the determination index indicates
that larger system capacity is required. For example, in the macro cell 12, when the
6 determination index relating to the system capacity requirements is the lowest value,
the operation modes are set to be a standby mode for all the small cell groups G21,
G22, G23 and G24. When the determination index increases to some extent, as
illustrated with the shaded segment in FIG. 9A, the mode determining unit 154
activates the small cell group G21. When the determination index further increases,
10 as illustrated with the shaded segment in FIG. 9B, the mode determining unit 154
activates the small cell group G22 in place of the small cell group G21. When the
determination index continues to further increase, the mode determining unit 154 can
sequentially activate the small cell group G23 in place of the small cell group G22,
and furthel; the small cell group G24 in place of the small cell group G23.
15 [0052]
(3) Control of Operation Mode for Each Sector
In the above-described first configuration example and the second
configuration example of the small cell groups, the macro cell 12 can correspond to
the management area. Meanwhile, FIG. 10 illustrates an example where each sector
20 of the macro cell 12 corresponds to the management area. Referring to FIG. 10, the
macro cell 12 is divided into six sectors 14a to 14f. The mode determining unit 154
can determine the operation modes in units of the small cell groups separately for
these sectors 14a to 14f. For example, a ratio of the active small cells is 75% in the
sector 14a, 0% in the sector 14b, 50% in the sector 14c, 0% in the sector 14d, 0% in
25 the sector 14e and 25% in the sector 14f.
[0053]
[2-3. Control Message]
(1) First Example
FIG. 11A is an explanatory diagram illustrating one example of a control
30 message corresponding to the first configuration example of the small cell groups.
Refening to FIG. 11A, the control message 161a includes a message type field 162
and an operation mode field 164. The message type field 162 indicates a code "TI"
which means that the control message 161a is a message for specifying the operation
modes in units of the small cell groups. The operation mode field 164 includes four
flags respectively having a length of one bit here. The first bit of the operation
5 mode field 164 is a flag meaning whether the small, cell group GI1 should be
activated. When the first flag is "I", the small cell group GI1 is activated, while,
when the flag is "0", the snlall cell group GI1 is deactivated. The second bit of the
operation mode filed 164 is a flag meaning whether the small cell group G12 should
be activated. When the second flag is "I", the sniall cell group G12 is activated,
10 while, when the flag is "0", the small cell group G12 is deactivated. The third bit of
the operation mode field 164 is a flag meaning whether the small cell group G13
should be activated. When the third flag is "I", the small cell group G13 is
activated, while, when the flag is "On, the small cell group G13 is deactivated. The
fourth bit of the operation mode field 164 is a flag meaning whether the small cell
15 group G14 should be activated. When the fourth flag is "I", the small cell group
G14 is activated, while, when the flag is "0", the small cell group G14 is deactivated.
In the example of FIG. 1 lA, because the bit sequence of the operation mode field 164
is "1100", the operation modes of the small cells belonging to the small cell groups
G11 and GI2 can be set to be the active mode, and the operation modes of the small
20 cells belonging to the small cell groups G13 and GI4 can be set to be the standby
mode.
[0054]
According to such a format of the control message, it is possible to
dynamically control the operation modes of a number of small cell base stations 20
25 operating within the macro cell 12 explained using FIG. 6 only by signaling the bit
sequence of only four bits (for example, broadcasting the bit sequence within the
management area).
[OOSS]
(2) Second Example
30 FIG 11B is an explanatory diagram illustrating one example of a control
message corresponding to the second configuration example of the small cell groups.
Refei~ingto FIG. 11B, the control message 161b includes a message type field 162
and an active group field 166. The active field group 166 indicates identification
information of the small cell group for which it is determined that thc active mode
should be set. In the example of FIG. 11B, the active group field 166 includes only
5 a group ID of the small cell group G22. Therefore, the operation modes of the
small cells belonging to the small cell group G22 can be set to be the active mode,
and the operatioil modes of the small cells not belonging to the snlall cell group G22
can be set to be the standby mode.
[0056]
10 According to such a format of the control message, it is possible to
dynan~ically control the operation modes of a number of small cell base stations 20
operating within the macro cell 12 explained using FIG. 8 only by signaling
identification information of one (or a small number of) small cell group (for
example, broadcasting the identification information within the management area).
15 [0057]
The control messages illustrated in FIG. 11A and FIG. 11B may be defined
as messages which are newly introduced. Alternatively, these control messages
may be defined by, for example, using an existing message such as a multicast
message for discontinuous transmission (DTX)/discontinuous reception (DM)
20 control.
[OOSS]
[2-4. Data Configuration]
(1) Small Cell Data
FIG. 12 is an explanatory diagram illustrating one example of a
25 configuration of small cell data 13 which can be stored by the storage unit 130.
Referring to FIG. 12, the small cell data 131 includes ten data items of a cell ID 132,
a cell radius 133, a base station (BS) location 134, the maximum number of
accommodated terminals 135, a BS type 136, an available channel 137, an operation
channel 138, the number of accommodated terminals 139, a band use rate 140 and a
30 groupID141.
[0059]
The cell ID 132 is an identifier for uniquely identifying each small cell (or a
small cell base station). The cell radius 133 and the BS location 134 are
information specifying coverage of each small cell. The cell radius 133 indicates a
radius of the coverage of each small ccll. The cell radius may be calculated from
5 parameters such as maximum transmission power of each small cell base station,
antenna gain and antenna height. The BS location 134 indicates a geographical
location (latitude, longitude and altitude) of each small cell base station. The
maxinlum number of accommodated terminals 135 indicates a maximum value of the
number of terminals which can be accommodated by each small cell base station.
10 The BS type 136 indicates whether each small cell base station is a fixed base station
or a mobile base station (that is, a dynamic AP). The available channel 137
indicates a list of available channels which are allocated to each small cell or which
are supported by each small cell base station. Each channel can be identified using,
for example, a band number of international mobile telecommunication (IMT). The
15 operation channel 138 indicates a list of channels actually used for operation of each
small cell. The number of accommodated terminals 139 indicates the number of
terminals connected to each small cell at that time. The band use rate 140 indicates
a proportion of actually measured traffic to the band of each small cell. The group
ID 141 indicates an identifier (or a list of identifiers) for identifying a small cell
20 group to which each small cell belongs.
[0060]
Among these data items, the cell radius 133 and the BS location 134 can be
registered when operation of each small cell is started, and can be updated every time
the small cell base station moves or the configuration is changed. The maximum
25 number of accommodated terminals 135 and the BS type 136 can be registered when
the operation of each small cell is started. The available channel 137 can be
allocated when the operation of each small cell is started and can be signaled to each
small cell base station from the signaling unit 156. The operation channel 138 can
be selected by each small cell base station amolig the signaled available channels and
30 can be reported to the comnlunication control apparatus 100. The nunlber of
acconlmodated terminals 139 and the band use rate 140 call be monitored by the
mode determining unit 154 and can be updated as needed while each small cell
operates in the active mode. The group ID 141 can be allocated to each snlall cell
by the mode dete~lnining unit 154 when the operation of each small cell is started,
and can be signaled to each small cell base station from the signaling unit 156.
5 Allocation of the small cell groups to each small cell may be updated depending on
change of a communication state within the management area.
[0061]
The small cell data 131 illustrated in FIG. 12 includes only a record
associated with one given small cell within the management area. However, the
10 present disclosure is not limited to this example, and the small cell data 131 may
include a record associated with a number of small cells existing over a plurality of
management areas (for example, a plurality of sectors or a plurality of macro cells).
[0062]
(2) Operation Mode Table
15 FIG 13 is an explanatory diagram illustrating one example of a
configuration of the operation mode table 145 which can be stored by the storage
unit 130. The operation mode table 145 includes four data items of a pattern ID 146,
a capacity range 147, a terminal number range 148 and an operation mode pattern
149.
20 [0063]
The pattern ID 146 is an identifier for uniquely identifying each record of
the operation mode table 145. The capacity range 147 indicates a range of system
capacity of the management area, which is associated with each record. Here, the
system capacity can be expressed with, for example, the number of bits which can be
25 processed per unit time (that is, throughput). The terminal number range 148
indicates a range of the total number of terminals which are accommodated in the
macro cell and the small cells in the management area, which is associated with each
record. The operation mode pattern 149 indicates a setting pattern of the opcration
mode for each small cell group. The capacity range 147 and the terminal number
30 range 148 can be updated when allocation of the snlall cell to each small cell group is
changed.
[0064]
111 the example of FIG. 13, it is assumed that a (actually mcasurcd or
predicted) traffic amount is used as the determinat~oni ndex relating to the system
capacity requirements, and the latest traffic amount CCumnist smaller than Co. In
5 this case, the mode determining unit 154 refers to a record of the pattern ID = "PTO"
having the capacity range 147 conforming to the latest traffic amount C,,,,,,,,. Then,
the mode determining unit 154 can determine that the operation modes of all the
small cell groups G11, G12, GI3 and G14 should be set to be the standby mode
based on content of the operation mode pattern 149 of the record. When the latest
10 traffic amount C,,,,,,, is greater than Co and smaller than CI, the mode determining
unit 154 refers to a record of the pattern ID = "PTI" having the capacity range 147
conforming to the latest traffic amount C,,,,,,,. Then, the mode determining unit
154 can activate only the small cell group GI1 based on content of the operation
mode pattern 149 of the record. When the latest traffic amount CCumnist greater
15 than C1 and smaller than Cz, the mode determining unit 154 refers to a record of the
pattern ID = "PT2" having thc capacity range 147 conforming to the latest traffic
amount C,,,,,t. Then, the mode determining unit 154 can activate the small cell
groups GI1 and G12 based on content of the operation mode pattern 149 of the
record.
20 [0065]
In the example of FIG. 13, it is assumed that the number of accommodated
terminals is used as the determination index relating to the system capacity
requirements, and the latest number of accommodated terminals N,,,,,,,t is smaller
than No. In this casc, the mode determining unit 154 refers to a record of the pattern
25 ID = "PTO" having the capacity range 147 conforming to the latest number of
accommodated terminals N,,,,,,. Then, the mode determining unit 154 can
determine that the operation modes of all the small cell groups G11, G12, G13 and
GI4 should be set to be the standby mode based on content of the operation mode
pattern 149 of the record. When the latest number of accommodated terminals
30 N,,,,,,, is greater than No and smaller than NI, the mode determining unit 154 refers
to a record of the pattern ID = "PT1" having the capacity range 147 conforming to
the latest number of accommodated terminals N,,,,,,,t. Then, the mode determining
unit 154 can activate only the slnall cell group G11 based on content of the operation
mode pattern 149 of the record. When the latest number of accon~modated
terminals NCurenits greater than Nt and smaller than Nz, the mode determining unit
5 154 refers to a record of the pattern ID = "PTY having the capacity range 147
conforming to the latest number of accommodated terminals N,,,,,,. Then, the
mode determining unit 154 can activate the small cell groups GI1 and GI2 based on
content of the operation mode pattern 149 of the record.
[0066]
10 It should be noted that when capacity or the number of accommodated
terminals expected for each small cell group is dynamically calculated, the storage
unit 130 does not have to store the operation mode table 145 as illustrated in FIG. 13.
Further, one of the capacity range 147 and the terminal number range 148 may be
omitted.
15 [0067]
(3) Calculation of Capacity
The system capacity in the management area corresponds to a sum of the
capacity of the macro cell (or a sector of the macro cell) in the management area and
the capacity of zero or one or more small cells operating in the active mode in the
20 management area. As one example, the capacity of each cell can be calculated as
follows. It should be noted that it is assumed here that each cell is operated
according to the LTE scheme.
100681
First, the number of resource blocks in a frequency direction of the 1-th
25 frequency channel used by the x-th small cell SCk,. belonging to the k-th small cell
group within the management area is set at NRB(~X,, 1). NRB(~X,, 1) can be derived
from a bandwidth of the frequency channel, and, for example, the number of
resource blocks in the frcquency direction of an IMT band having a bandwidth of 20
MHz is 100. Further, when the number of coding bits per one resource bloclc is set
30 at Nee - RB,t he number of coding bits Mc~(kx, , I) per one second which can be
processed on the I-th frequency channel of the small cell SCk,. can be expressed with
the followiilg equation.
[0069]
[Math 11
5 [0070]
It should be noted that in the above equation, Mod indicates a modulation
order. Nsynlbnw~h ich indicates the number of modulation symbols per one resource
block, is equal to a product of the number of symbols (six or seven) in a time
direction and the number of subcarriers (twelve). NR~NCc,f rl and Nsyncr espectively
10 indicate the number of reference signals, the number of control signals and the
number of synchronization signals per one resource block. A function F typically
derives a number obtained by rcrnoving a bit for control from all the bits calculated
from the number of modulation symbols per one resource block and the modulation
order. The number of data bits MDB(~X,, 1) per one second which can be processed
15 on the 1-th frequency channel of the small cell SCI,, can be expressed with the
following equation by counting a coding rage Rcade in the equation.
[Math 21
[0071]
20 In equation (2), Mrail indicates the number of tail bits added upon coding.
The number of data bits Mo~(kx, ) per one second which can be processed by the
small cell SCI,,. can be expressed with, for example, the following equation.
[Math 31
[0072]
In equation (3), a parameter a indicates an adjustment margin, and a
parameter p indicates the number of MIMO streams. Mo~(kX, ) can correspond to
5 capacity which is expected for each small cell. The system capacity (throughput) in
the management area can be calculated using the following equation by counting the
above-described capacity.
[Math 41
10
[0073]
In equation (4), MDB-M ~~~~i s expected capacity of the macro cell (or the
sector).
[0074]
15 [2-5. Processing Flow]
(1) Control Sequence
FIG. 14 is a sequence diagram illustrating one example of flow of
communication control processing according to one embodiment. The sequence
illustrated in FIG. 14 is involved by the communication control apparatus 100 which
20 corresponds to the macro cell base station 10, the small cell base stations 20a and
20b, the terminal apparatuses 30a and 30b and the core network node 50.
[0075]
At the beginning of the sequence, the small cell base station 20a operates in
the standby mode, and the small cell base station 20b operates in the active mode.
25 The tenninal apparatus 30a is connected to the macro cell base station 10, and the
terminal apparatus 30b is connected to the small cell base station 20b. For example,
the core network node 50 transmits downlink traffic addressed to the terminal
apparatus 30a to the macro cell base station 10 (step S10). The macro cell base
station 10 transfers the downlink traffic to the terminal apparatus 30a (step S12).
Further, for example, the terminal apparatus 30b transmits uplink traffic to the s~uall
cell base station 20b (step S14). The small cell base station 20b transfers the uplink
5 traffic to the macro cell base station 10 (step S l6), and the macro cell base station 10
further transfers the uplink traffic to the core network node 50 (step S 18).
[0076]
The mode determining unit 154 of the communication control apparatus 100
continuously monitors a connection state and a communication state of the terminals
10 (step S20). The mode determining unit 154 then executes operation mode
determination processing using the determination index relating to the system
capacity requirements (step S30). Through the operation mode determination
processing here, the operation modes in units of the small cell groups are determined.
It should be noted that some examples of the detailed flow of the operation mode
16 determination processing will be described later.
[0077]
When the operation modes in units of the small cell groups are determined,
the signaling unit 156 signals a control message for specifying the determined
operation modes to the small cell base stations 20a and 20b on the back haul link
20 (step S40). Further, the signaling unit 156 may report the determination result of
the operation modes to the core network node 50 such as the MME (step S45).
[0078]
Here, it is assumed as one example that the control message indicates that
the small cell group to which the small cell base station 20a belongs should be
25 activated (and the active mode of the small cell group to which the small cell base
station 20b belongs should be maintained). The small cell base station 2021 activates
the small cells operated by the small cell base station 20a according to the control
message received from the comnunicatio~cl ontrol apparatus 100 (step S50).
[0079]
30 When the small cells operated by the small cell base station 20a are
activated, the terminal apparatus 30a located in the vicinity of the small cell base
station 20a can receive a reference signal transmitted from thc small cell base station
20a (step S55). The terminal apparatus 30a executes measurement according to, for
example, an instruction from the macro cell base station 10 which is a serving base
station or according to a periodic timing and measures quality of the reference signal
5 for serving cells and adjacent cells (step S60). The adjacent cells described here
include small cells operated by the small cell base station 2021. It should be noted
that when the terminal apparatus 30a is put into the standby state, cell search can be
executed instead of measurement.
[0080]
10 Subsequently, the terminal apparatus 30a transmits a measurement report
including a list of quality indices as a result of the measurement to the macro cell
base station 10 (step S65). It is assumed here that the transmitted measurement
report indicates that the small cells operated by the small cell base station 20a exhibit
the best quality. In this case, handover procedure which uses the macro cell base
15 station 10 as a source base station and uses the small cell base station 20a as a target
base station is executed, triggered by the measurement report (step S70). The
terminal apparatus 30a tries to connect to the activated small cells of the small cell
base station 20a by, for example, transmitting a random access signal (step S80).
[008 11
20 (2) Operation Mode Determination Processing - First Example
FIG. 15A is a flowchart illustrating a first example of flow of the operation
mode determination processing illustrated in FIG. 14. In the first example, the
mode determining unit 154 uses an actual traffic amount actually occurring in the
management area as the determination index and refers to the operation mode table
25 145 stored by the storage unit 130.
[0082]
Refelring to FIG. 15A, first, the mode determining unit 154 acquires a total
traffic amount TR actually occurring within a given time window in the manageinent
area (step S110). The mode determining unit 154 then acquires the corresponding
30 operation modes in units of the small cell groups by referring to the operation mode
pattern of the record having the capacity range to which the total traffic amount TR
belongs (step S115). It should bc noted that when a plurality of operation mode
tables 145 with different operation mode patterns are prepared, the mode determining
unit 154 may switch the operation mode table to be referred to according to, for
example, temporal conditions (the same also applies to other examples of the
5 operation mode determination processing).
[0083]
The mode determining unit 154 then adjusts the opelation modes depending
on statuses (such as, for example, normally operatedlfailed and a residual battery
amount being small) of the individual small cell base stations (step S130). For
10 example, when it is predicted that some small cell base stations cannot operate and
the system capacity becomes insufficient, one or more small cell groups may be
additionally activated. When the residual battery amount of a battery-driven small
cell base station falls below a threshold, the small cell base station may be excluded
from the small cell group (or from calculation of capacity) until the residual battery
15 amount exceeds the threshold through charging. It should be noted that the
adjustment of the operation modes here may be omitted.
[0084]
Subsequently, the signaling unit 156 determines whether the operation
modes determined or adjusted by the mode determining unit 154 include updating
20 from the operation modes at the time of the previous signaling (step S135). Here,
when the opelation mode of none of the small cell groups is updated, the following
processing is skipped. When the operation modes are updated, the signaling unit
156 generates a control message for specifying the latest operation modes in units of
the small cell groups (step S140). The signaling unit 156 then broadcasts (or
25 multicasts) the generated control message to one or more small cell base stations 20
within the management area (step S145).
[OOSS]
(3) Operation Mode Determination Processing - Second Example
FIG. 15B is a flowchart illustrating a second example of the flow of the
30 operation mode deteimination processing illustrated in FIG. 14. In the second
example, the mode determining unit 154 uses a predicted traff~ca mount which is
predicted to occur in the management area as the determination index, and refers to
the operation mode table 145 stored by the storage unit 130.
[0086]
Referring to FIG. 15B, first, the mode determining unit 154 counts a
5 predicted traffic amount ET based on QoS classes of the tern~inals existing in the
management area (step S111). As one example, the QoS class includes the
following four types of classes.
-"Conversational" class: voice call, VoIP, video conference, or the like
-"Streaming1' class: real-time video delivery, or the like
-"Interactiven class: web access, database search, or the like
-"Background" class: e-mail, SMS, or the like
These four types of QoS classes have respectively different capacity
requirements, and different attributes are defined for each QoS class (or traffic class).
The attributes described here include, for example, a maximum bit rate, a delivery
15 order, a bit error rate, a guaranteed bit rate, transfer delay, traffic processing priority,
or the like. Therefore, the mode determining unit 154 can count the predicted
traffic amount ET using these attribute information for each of the QoS classes of the
terminals. For example, it is also possible to calculate a sum of the guaranteed bit
rates of terminals belonging to the "Conversational" class or the "Streaming" class
20 which has high priority as the predicted traffic amount ET. Alternatively, it is also
possible to calculate a sum of maximu11 bit rates of terminals of all the classes as the
predicted traffic amount ET.
[0087]
Subsequently, the mode determining unit 154 acquires the corresponding
25 operation modes in units of the small cell groups by referring to the operation mode
pattern of the record having the capacity range to which the predicted traffic amount
ET belongs in the operation mode table 145 (step S116).
[0088]
Subsequently, the mode deternlining unit 154 adjusts the operation modes
30 depending on statuses of the individual small cell base stations (step S130). It
should be noted that the adjustment of the operation modes here nlay be omitted
Subsequently, the signaling unit 156 determines whether the operation
modes determined or adjusted by the mode determining unit 154 include updating
from the operation modes at the time ofthe previous signaling (step S135). When
5 the operation modes are updated, the signaling unit 156 generates a control message
for specifying the latest operation modes in units of the small cell groups (step S140).
The signaling unit 156 then broadcasts (or multicasts) the generated control message
to one or more small cell base stations 20 within the management area (step S145).
[0090]
10 (4) Operation Mode Determination Processing - Third Example
FIG. 15C is a flowchart illustrating a third example of the flow of the
operation mode determination processing illustrated in FIG. 14. In the third
example, the mode determining unit 154 uses the number of terminals existing in the
management area as the determination index and refers to the operation mode table
15 145 stored by the storage unit 130.
[009 11
Referring to FIG. 15C, first, the mode determining unit 154 counts the total
number NUE of the terminals existing in the management area (step S112).
Subsequently, the mode determining unit 154 acquires the corresponding operation
20 modes in units of the small cell groups by referring to the operation mode pattern of
the record having the terminal number range to which the total number NUE of the
terminals belong in the operation mode table 145 (step S117).
[0092]
Subsequently, the mode determining unit 154 adjusts the operation modes
25 depending on statuses of the individual small cell base stations (step S130). It
should be noted that the adjustment of the operation modes here may be omitted.
[0093]
Subsequently, the signaling unit 156 determines whether the operation
modes determined or adjusted by the mode determining unit 154 include updating
30 fiom the operation mode at the time of the previous signaling (step S135). When
the operation modes are updated, the signaling unit 156 generates a control message
for specifying the latcst operation modes in units of the small cell groups (step S140).
The signaling unit 156 then broadcasts (or multicasts) the generated control message
to one or more small cell base stations 20 within the management area (step S145).
[0094]
5 (5) Operation Mode Determination Processing - Fourth Example
FIG. 15D is a flowchart illustrating a fourth example of the flow of the
operation mode determination processing illustrated in FIG. 14. In the fourth
example, the mode determining unit 154 uses an actual traflic amount actually
occurring in the management area as the determination index. The operation mode
10 table 145 is not referred to.
[0095]
Referring to FIG. 15D, first, the mode determining unit 154 acquires a total
traffic amount TR actually occurring within a given time window in the management
area (step S110). Subsequently, the mode determining unit 154 calculates system
15 capacity of the management area, that is, total capacity TC which is equal to a sum of
the capacity of the macro cell (or the sector) and the capacity of active small cells
(step S118).
[0096]
Subsequently, the mode determining unit 154 compares the total traffic
20 amount TR with the total capacity TC (step S120, S121). Here, when a difference
obtained by subtracting the total traffic amount TR from the total capacity TC
(hereinafter, referred to as a capacity gap) falls below a threshold Thl, because the
capacity is actually insufficient or there is a risk that the capacity may be insufficient,
the mode determining unit 154 activates one of the small cell groups which are put
25 into the standby state (step S124). Furthel; when the capacity gap exceeds a
threshold Th2 (the threshold Th2 is a positive value and greater than the threshold
Thl), because there is sufficient capacity, the mode determining unit 154 deactivates
one of the active small cell groups (step S127). Such adjustment of the operation
modes and recalculation of the system capacity TC are repeated until the capacity
30 gap falls within a range spccified with the threshold Thl and the threshold Th2.
[0097]
It should be noted that excess or shortage of the capacity may be adjusted at
least partially by reducing or increasing transnlission power of the small cell base
stations which operate in the active mode at that time.
[0098]
5 When the capacity gap falls within the range specified with the threshold
Thl and the threshold Th2, the signaling unit 156 determines whether the determined
operation modes include updating from the operation modes at the time of the
previous signaling (step S135). When the operation modes are updated, the
signaling unit 156 generates a control message for specifying the latest operation
10 modes in units of the sinall cell groups (step S140). The signaling unit 156 then
broadcasts (or multicasts) the generated control message to one or more small cell
base stations 20 in the management area (step S145).
[0099]
(6) Operation Mode Determination Processing - Fifth Example
15 FIG. 15E is a flowchart illustrating a fifth example of the flow of the
operation mode determination processing illustrated in FIG. 14. In the fifth
example, the mode determining unit 154 uses an actual traffic amount actually
occurring in the management area as the determination index. The operation mode
table 145 is not referred to. The operation modes of the small cell groups to which
20 a dynamic cell does not belong are preferentially set to be the active mode over the
small cell groups to which a dynamic cell belongs.
[OlOO]
Referring to FIG. 15E, first, the mode determining unit 154 acquires a total
traffic amount TR actually occurring within a given time window in the management
25 area (step S110). Subsequently, the mode determining unit 154 calculates system
capacity ofthe management area, that is, total capacity TC which is equal to a sum of
the capacity of the macro cell (or the sector) and the capacity of active small cells
(step S 11 8).
[OlOl]
30 Subsequently, the mode determining unit 154 compares the total traffic
amount TR with the total capacity TC (step S120, S121). Here, when a capacity
gap which is a difference obtained by subtracting the total traffic amount TR from
the total capacity TC falls below the tlveshold Thl, the mode determining unit 154
selects one of the small cell groups which are put into the standby state (step S122).
Here, when there is a small cell group which does not include a dynamic ccll, the
5 mode determining unit 154 preferentially selects the small ccll group. The mode
determining unit 154 then activates the selected small cell group (step S123).
Further, when the capacity gap exceeds the threshold Th2, the mode determining unit
154 selects one of the active small cell groups (step S125). Here, when there is a
small cell group which includes a dynamic cell, the mode determining unit 154
10 preferentially selects the small cell group. The mode determining unit 154 then
deactivates the selected small cell group (step S126). Such adjustment of the
operation modes and recalculation of the system capacity TC are repeated until the
system gap falls within the range specified with the threshold Thl and the threshold
Th2.
15 [0102]
When the capacity gap falls within the range specified with the threshold
Thl and the threshold Th2, the signaling unit 156 determines whether the determined
operation modes include updating from the operation modes at the time of the
previous signaling (step S135). When the operation modes are updated, the
20 signaling unit 156 generates a control message for specifying the latest operation
modes in units of the small cell groups (step S140). The signaling unit 156 then
broadcasts (or multicasts) the generated control message to one or more small cell
base stations 20 within the management area (step S145).
[0103]
25 By preferentially utilizing the fixed small cell base station instead of the
dynamic AP as in the fifth example, it is possible to, for example, minimize change
of the configuration due to movement of the base station or battery shortage, so that
it is possible to secure stable operation of the system.
[0 1041
30 It should be noted that any combination of the exan~ples of the operation
mode determination processing explained using FIG. 15A to FIG. 15E is possible.
[0105]
13. Configuration Example of Radio Comnlunication Apparatus>
[3-1. Configuration of Each Unit]
FIG. 16 is a block diagram illustrating one example of a configuration of the
5 small cell base station 20 according to the present embodiment. Referring to FIG.
16, the small cell base station 20 includes a radio communication unit 210, a network
communication unit 220, a storage unit 230 and a control unit 240.
[0 1061
(1) Radio Communication Unit
10 The radio communication unit 210 provides second radio communication
service to the terminal apparatuses 30 located within the small cells 22 disposed
within the macro cell 12. The small cells 22 belong to at least one of a plurality of
small cell groups. For example, the radio communication unit 210 transmits a
reference signal on downlink in the active mode. The reference signal is searched
15 by the terminal apparatuses 30 during procedure of cell selection or cell reselection.
Furthel; the terminal apparatuses 30 derive communication quality for each cell
which becomes a basis of handover determination by executing measurement for the
reference signal.
[0 1071
20 (2) Network Communication Unit
The network communication unit 220 establishes a back haul link with the
macro cell base station 10, and mediates communication between the small cell base
stations 20 and the macro cell base station 10. It should be noted that the back haul
link may be part of the radio link established by the radio communication unit 210.
25 In this case, the network communication unit 220 can be omitted from the
configuration of the small cell base station 20.
[0108]
(3) Storage Unit
The storage unit 230 stores a program and data for operation of the small
30 cell base station 20 using a storage medium such as a hard disc and a selniconductor
memory.
[0 1091
(4) Control Unit
The control unit 240 controls gcncral operation of the small cell base station
20 using a processor such as a CPU and a DSP. In the present embodiment, the
5 co~ltroul nit 240 includes a co~nmunicationc ontrol unit 242 and a mode setting unit
244.
[0110]
The communication control unit 242 controls provision of the second radio
communication service. For example, the comn~unication control unit 242 makes
10 the network communication unit 220 transfer uplink data traffic received by the radio
communication unit 210 to the macro cell base station 10 depending on its address.
Further, the communication control unit 242 makes the radio communication unit
210 transmit downlink data traffic received from other nodes by the network
communication unit 220 to the terminal apparatus 30 to which the downlink data
15 traffic is addressed.
[Olll]
The mode setting unit 244 sets the operation modes of the radio
con~municationu nit 210 and the communication control unit 242 to be one of the
operation mode candidates including the above-described active mode and the
20 standby mode. When the back haul link is established, the mode setting unit 244,
for example, registers information relating to coverage of the own apparatus and
information such as the maximum number of accommodated terminals and the base
station type in the con~munication control apparatus 100. Further, the mode setting
unit 244 receives an allocation message indicating allocation of available channels
25 and group IDS fi-om the communicalion control apparatus 100. The mode setting
unit 244 identifies the small cell groups which are allocated to the own apparatus by
referring to the allocation message. Further, the Inode setting unit 244 receives a
control message for specifying the operation modes in units of the small cell groups
signaled from the communication control apparatus 100. The control message
30 specifies tlie operation modes determined by the communication control apparatus
100 for the small cell goups to which the small cells operated by each small cell
base station belong. Thc mode setting unit 244 then sets the operation modes of the
radio con~munication unit 210 and the co~n~nunicatiocno ntrol unit 242 according to
the received control message.
[0112]
5 For example, concerning the control message 161a illustrated in FIG. 11A,
when the own group is a small cell group G11, the mode setting unit 244 sets the
operation modes of the radio communication unit 210 and the colnmunication control
unit 242 to be the active mode if the first bit of the operation mode field 164 is "I".
On the other hand, the mode setting unit 244 sets the operation modes of the radio
10 communication unit 210 and the colnmunication control unit 242 to be the standby
mode if the first bit of the operation mode field 164 is "0".
[0113]
Further, for example, concerning the control message 161b illustrated in FIG.
11B, when the own group is a small cell group G21, the mode setting unit 244 sets
15 the operation modes of the radio communication unit 210 and the communication
control unit 242 to be the active mode if the active group field 166 includes group ID
"G21". On the other hand, the mode setting unit 244 sets the operation modes of
the radio communication unit 210 and the communication control unit 242 to be the
standby mode if the active group field 166 does not include the group ID "G21".
20 [0114]
The mode setting unit 244 continuously monitors signaling from the
communication control apparatus 100. The mode setting unit 244 confirms the
operation modes specified by the received message every time the above-described
broadcasted or multicasted control message is received. When the specified
25 operation modes of the groups are different from the currently set operation modes,
the mode setting unit 244 changes setting of the operation modes.
[0115]
In one modified example, the small cell base station 20 may independently
determine allocation of the small cell groups to the small cells operated by the radio
30 connnunication unit 210 without requiring signaling from the con~rnunicationc ontrol
apparatus 100, that is, without receiving the above-described allocation message.
The allocation of the small cell groups can bc, for example, determined from
geographical location of the small ccll base station 20 based on mapping of the
segments and the small cell groups as illustrated in FIG. 6 or FIG. 8. For example, it
is assumed that the small cell base station 20 is a mobile terminal which can
5 temporarily operate the dynamic cell, that is, a dynamic AP. Mobility of the
dynamic AP can cause frequency change of allocation of the small cell groups to the
dynamic AF'. However, when the dynamic AP independently determines allocation
of the small cell groups, because it is not necessary to signal the allocation message,
it is possible to avoid increase of a signaling overhead due to frequency change of
10 allocation of the small cell groups. The mapping of the geographical segments and
the small cell groups may be broadcasted by the communication control apparatus
100 or may be downloaded by the small cell base station 20 from some data server.
[0116]
[3-2. Processing Flow]
15 FIG. 17A is a flowchart illustrating a first example of flow of operation
mode setting processing which can be executed by the small cell base station 20.
[0117]
Referring to FIG. 17A, first, the mode setting unit 244 receives an allocation
message indicating allocation of the small cell groups (step S210). Subsequently,
20 the mode setting unit 244 waits for reception of the control message for specifying
the operation modes in units of the small cell groups from the communication control
apparatus 100 (step S220). When the control message is received, the mode setting
unit 244 identifies the operation modes of the small cell groups to which the own
apparatus belongs, specified by the control message (step S230). The mode setting
25 unit 244 then sets the operation modes of the radio communication unit 210 and the
communication control unit 242 to be the identified mode (step S240).
[0118]
FIG. 17B is a flowchart illustrating a second example of the flow of the
operation mode sctting processing which can be executed by the small cell base
30 station 20. In the second example, the small cell base station 20 is a dynamic AP.
[0119]
Referring to FIG. 17B, first, the mode setting unit 244 acquires small cell
group determination information for determining allocation of the small cell groups
(step S210). The small cell group determination information maps, for example, the
geographical segments within the management area and the corresponding small cell
5 groups. Subsequently, the mode setting unit 244 determines allocation of the small
cell groups to the dynamic cells operated by the small cell base station 20 (step S215).
Subsequently, the mode setting unit 244 waits for reception of the control message
for specifying the operation modes in units of the small cell groups from the
communication control apparatus 100 (step S220). When the control message is
10 received, the mode setting unit 244 identifies the operation modes of the small cell
groups to which the small cell base station 20 belongs, specified by the control
message (step S230). The mode setting unit 244 then sets the operation modes of
the radio communication unit 210 and the communication control unit 242 to be the
identified mode (step S240). Further, the mode setting unit 244 determines whether
15 the small cell base station 20 moves (step S250). When the small cell base station
20 does not move, the operation mode setting processing returns to step S220 in
which reception of the control message is waited. When the small cell base station
20 moves, allocation of the small cell groups to the dynamic cells operated by the
small cell base station 20 is determined again according to SCG determination
20 information.
[O 1201
14. Application to Spectrum Access System (SAS)>
In discussion regarding frequency usage by the Federal Con~munications
Commission (FCC), a 3 tiered model in which players performing spectrum access
25 are classified into three categories as illustrated in FIG. 18 is proposed. A player of
a top tier T1 is a primary user (incumbent access user) who is legally authorized. A
player of intermediate tier T2 is a priority user (priority access user) to whom usage
is approved secondarily but preferentially. A player of a bottom tier T3 is a general
user (generalized authorized access user) to whom requirements for approval are not
30 strict although usage is limited to usage at close range or usage at low transmission
power, or indoor usage. In an SAS of such a 3 tiered model, the above-described
communication control apparatus 100 may be introduced by a player of any tiers (or
the third party). For example, by coordinately controlling the operation modes of
the small cells operated by the priority user (and the general user) in units of the
small cell groups, it is possible to maintain optimal capacity of the SAS and optimal
5 power consunlption ofthe whole system with a small signaling overhead.
[0121]
1 5 . Application Example>
The technique according to the present disclosure can be applied to various
products. For example, a management server which controls the operation modes
10 of the small cells as an upper node of the macro cell base station 10 can be realized
in a form of a tower server, a rack server, a blade server, or the like. Further, in a
control module (for example, an integrated circuit module configured with one die or
a car or a blade to be inserted into a slot of the blade server) mounted on the
management server, an operation mode control function for the small cells may be
15 realized.
[0122]
For example, the macro cell base station 10 and the small cell base station
20 may be realized as any type of evolved Node B (eNB). A small eNB may be an
eNB that covers a cell smaller than a macro cell, such as a pico eNB, micro eNB, or
20 home (femto) eNB. Instead, the macro cell base station 10 and the small cell base
station 20 may be realized as any other types of base stations such as a NodeB and a
base transceiver station (BTS). The macro cell base station 10 may include a main
body (that is also referred to as a base station apparatus) configured to control radio
communication, and one or more remote radio heads (RRH) disposed in a different
25 place from the main body. Additionally, various types of terminals to be discussed
later may also operate as the small cell base station 20 by temporarily or semipermanently
executing a base station function.
[0123]
For example, a terminal apparatus 30 may be realized as a mobile terminal
30 such as a smartphone, a tablet personal computer (PC), a notebook PC, a portable
game terminal, a poi-tableldongle type mobile router, and a digital camera, or an invehicle
terminal such as a car navigation apparatus. The terminal apparatus 30 may
also be realized as a te~minal (that is also referred to as a MTC teiminal) that
performs M2M communication. Furthern~ore,a radio con~municationn lodule (such
as an integrated circuit module including a single die) mounted on the terminal
5 apparatus 30 may be provided.
[O 1241
[5- 1. Application Example Regarding Management Server]
FIG. 19 is a block diagram illustrating an example of a schematic
configuration of a management server 700 to which the technology of the present
10 disclosure may be applied. The management server 700 includes a processor 701, a
memory 702, a storage 703, a network interface 704, and a bus 706.
[0125]
The processor 701 may be, for example, a central processing unit (CPU) or
a digital signal processor (DSP), and controls functions of the server 700. The
15 memory 702 includes random access memory (RAM) and read only memory (ROM),
and stores a program that is executed by the processor 701 and data. The storage
703 may include a storage medium such as a semiconductor memory and a hard disk.
[O 1261
The network interface 704 is a wired communication interface for
20 connecting the server 700 to a wired communication network 705. The wired
communication network 705 may be a core network such as an Evolved Packet Core
(EPC), or a packet data network (PDN) such as the Internet.
[O 1271
The bus 706 connects the processor 701, the memory 702, the storage 703,
25 and the network interface 704 to each other. The bus 706 may include two or more
buses (such as a high speed bus and a low speed bus) each of which has different
speed.
[0128]
By the management server 700 illustrated in FIG. 19 playing a role of
30 controlling the operation modes in units of the small cell groups, even if a number of
small cells are deployed within the system, it is possible to integrally and
coordinately execute control of the operation modes of the small cells while
suppressing increase of the signaling overhead.
[0 1291
15-2. Application Examples Regarding Base Station]
5 (First Application Example)
FIG. 20 is a block diagram illustrating a first example of a schematic
configuration of an eNB to which the technology of the present disclosure may be
applied. An eNB 800 includes one or more antennas 810 and a base station
apparatus 820. Each antenna 810 and the base station apparatus 820 may be
10 connected to each other via an RF cable.
[0130]
Each of the antennas 810 includes a single or multiple antenna elements
(such as multiple antenna elements included in an MIMO antenna), and is used for
the base station apparatus 820 to transmit and receive radio signals. The eNB 800
15 may include the multiple antennas 810, as illustrated in FIG. 20. For exanlple, the
multiple antennas 810 may be compatible with multiple frequency bands used by the
eNB 800. Although FIG. 20 illustrates the exanlple in which the eNB 800 includes
the multiple antennas 810, the eNB 800 may also include a single antenna 810.
[0131]
20 The base station apparatus 820 includes a controller 821, a memory 822, a
network interface 823, and a radio communication interface 825.
[0132]
The controller 821 inay be, for example, a CPU or a DSP, and operates
various functions of a higher layer of the base station apparatus 820. For example,
25 the controller 821 generates a data packet from data in signals processed by the radio
comlnunication interface 825, and transfers the generated packet via the network
interface 823. The controller 821 may bundle data from ~nultiple base band
processors to generate the bundled packet, and transfer the generated bundled packet.
The controller 821 may have logical functions of perfo~nling control such as radio
30 resource control, radio bearer control, mobility management, admission control, and
scheduling. The control inay be perfor~ned in corporation with an eNB or a core
network node in the vicinity. Thc memory 822 includes RAM and ROM, and stores
a program that is executcd by the controller 821, and various types of control data
(such as a terminal list, transmission power data, and scheduling data).
[0133]
5 The network interface 823 is a comlnunication interface for connecting the
base station apparatus 820 to a core network 824. The controller 821 may
communicate with a core network node or another eNB via the network interface 823.
In that case, the eNB 800, and the core network node or the other eNB may be
connected to each other though a logical interface (such as an S1 interface and an
10 X2 interface). The network interface 823 may also be a wired communication
interface or a radio comn~unication interface for radio backhaul. If the network
interface 823 is a radio communication interface, the network interface 823 may use
a higher frequency band for radio communication than a frequency band used by the
radio communication interface 825.
15 [0134]
The radio communication interface 825 supports any cellular
communication scheme such as Long Term Evolution (LTE) and LTE-Advanced, and
provides radio connection to a terminal positioned in a cell of the eNB 800 via the
antenna 810. The radio communication interface 825 may typically include, for
20 example, a baseband (BB) processor 826 and an RF circuit 827. The BB processor
826 may perform, for example, encodingldecoding, modulatingldemodulating, and
multiplexingldemultiplexing, and performs various types of signal processing of
layers (such as L1, medium access control (MAC), radio link control (RLC), and a
packet data convergence protocol (PDCP)). The BB processor 826 may have a part
25 or all of the above-described logical functions instead of the controller 821. The
BB processor 826 may be a Inenlory that stores a communication control program, or
a module that includes a processor and a related circuit configured to execute the
program. Updating thc program may allow the functions of the BB processor 826
to be changed. The module may be a card or a blade that is inserted into a slot of
30 the base station apparatus 820. Alternatively, the module may also be a chip that is
mounted on the card or the blade. Meanwhile, the W circuit 827 may include, for
example, a mixer, a filtel; and an amplifier, and transinits and receives radio signals
via the antenna 810.
[0135]
The radio communication interface 825 may include the multiple BB
5 processors 826, as illustrated in FIG. 20. For example, the multiple BB processors
826 may be compatible with multiple frequency bands used by the eNB 800. The
radio communication interface 825 may include the multiple RF circuits 827, as
illustrated in FIG. 20. For example, the multiple RF circuits 827 may be compatible
with multiple antenna elements. Although FIG. 20 illustrates the example in which
10 the radio con~municationi nterface 825 includes the multiple BB processors 826 and
the multiple RF circuits 827, the radio communication interface 825 may also include
a single BB processor 826 or a single RF circuit 827.
[0136]
(Second Application Example)
15 FIG. 21 is a block diagram illustrating a second example of a schematic
configuration of an eNB to which the technology of the present disclosure may be
applied. An eNB 830 il~cludeso ne or more antennas 840, a base station apparatus
850, and an RRH 860. Each antenna 840 and the RRH 860 may be connected to
each other via an RF cable. The base station apparatus 850 and the RRH 860 may
20 be connected to each other via a high speed line such as an optical fiber cable.
[0137]
Each of the antennas 840 includes a single or multiple antenna elements
(such as multiple antenna elements included in an MIMO antenna), and is used for
the RRH 860 to transmit and receive radio signals. The eNB 830 may include the
25 multiple antennas 840, as illustrated in FIG. 21. For example, the multiple antennas
840 may be compatible with multiple frequency bands used by the eNB 830.
Although FIG. 21 illustrates the example in which the eNB 830 includes the multiple
antennas 840, the eNB 830 may also include a single antenna 840.
[0138]
30 The base station apparatus 850 includes a controller 851, a memory 852, a
network interface 853, a radio communicatioil interface 855, and a coilnection
interface 857. The controller 851, the memory 852, and tbe network interface 853
are the same as the controller 821, the memory 822, and the network interface 823
described with reference to FIG. 20.
[0139]
5 The radio co~ninunicatio~l interface 855 supports any cellular
communication scheme such as LTE and LTE-Advanced, and provides radio
communication to a terminal positioned in a sector corresponding to the RRH 860
via the RRH 860 and the antenna 840. The radio communication interface 855 may
typically include, for example, a BB pxocessor 856. The BB processor 856 is the
10 same as the BB processor 826 described with reference to FIG. 20, except the BB
processor 856 is connected to the RF circuit 864 of the RRH 860 via the connection
interface 857. The radio cominunication interface 855 may include the multiple BB
processors 856, as illustrated in FIG. 21. For example, the multiple BB processors
856 may be compatible with multiple frequency bands used by the eNB 830.
15 Although FIG. 21 illustrates the example in which the radio communication interface
855 includes the multiple BB processors 856, the radio communication interface 855
may also include a single BB processor 856.
[0140]
The connection interface 857 is an interface for connecting the base station
20 apparatus 850 (radio communication interface 855) to the RRH 860. The
connection interface 857 may also be a communication module for comn~unicationin
the above-described high speed line that connects the base station apparatus 850
(radio communication interface 855) to the RRH 860.
[0141]
25 The RRH 860 includes a connectio~l interface 861 and a radio
communication interface 863.
[O 1421
The connection interface 861 is an interface for connecting the RRI-I
860 (radio commu~licatioli interface 863) to the base station apparatus 850. The
30 co~lnectioiiln terface 861 may also be a con~n~unicatiolnno dule for comnluilication in
the above-described high speed line.
[O 1431
he radio connnunication interface 863 transmits and receives radio
signals via the antenna 840. The radio communication interface 863 may typically
include, for example, the RF circuit 864. The RF circuit 864 may include, for
5 example, a mixel; a filtel; and an amplifier, and transmits and receives radio signals
via the antenna 840. The radio communication interrace 863 may include multiple
RF circuits 864, as illustrated in FIG. 21. For example, the multiple RF circuits 864
may support multiple antenna elements. Although FIG 21 illustrates the example
in which the radio communication interface 863 includes the multiple RF circuits
10 864, the radio communication interface 863 may also include a single RF circuit 864.
[0 1441
The eNB 800 illustrated in FIG. 20 may be utilized as the small cell base
station 20 explained in the present specification. For example, the communication
control unit 242 and the mode setting unit 244 of the small cell base station 20 may
15 be implemented at the radio communication interface 825. Further, at least part of
these functions may be implemented at the controller 821.
[0145]
Further, the eNB 800 and eNB 830 illustrated in FIG. 20 and FIG. 21 may be
utilized as the macro cell base station 10 explained in the present specification. For
20 example, the communication control unit 152, the mode setting unit 154 and the
signaling unit 156 of the macro cell base station 10 may be implemented at the radio
con~munication interface 825, the radio communication interface 855 and/or the
radio communication interface 863. Further, at least part of these functions may be
implemented at the controller 821 and the controller 851.
25 [0146]
[5-3. Application Examples Regarding Terminal Apparatus]
(First Application Example)
FIG. 22 is a block diagram illustrating an example of a schematic
configuration of a smartphone 900 to which the technology of the present disclosure
30 may be applied. The smartphone 900 includes a processor 901, a incinory 902, a
storage 903, an external connection interface 904, a camera 906, a sensor 907, a
microphone 908, an illput device 909, a display device 910, a speaker 911, a radio
comn~uuication interface 912, one or more antenna switches 915, one or more
antennas 916, a bus 917, a battery 918, and an auxiliary controller 919.
[0147]
5 The processor 901 may be, for example, a CPU or a system on a chip (SoC),
and controls functions of an application layer and another layer of the smartphone
900. The memory 902 includes RAM and ROM, and stores a program that is
executed by the processor 901, and data. The storage 903 may include a storage
medium such as a semiconductor memory and a hard disk. The external connection
10 interface 904 is an interface for connecting an external device such as a memory card
and a universal serial bus (USB) device to the smartphone 900.
[0148]
The camera 906 includes an image sensor such as a charge coupled device
(CCD) and a complementary metal oxide semiconductor (CMOS), and generates a
15 captured image. The sensor 907 may include a group of sensors such as a
measurement sensol; a gyro sensor, a geomagnetic sensor, and an acceleration sensor.
The microphone 908 converts sounds that are input to the smartphone 900 to audio
signals. The input device 909 includes, for example, a touch sensor configured to
detect touch onto a screen of the display device 910, a keypad, a keyboard, a button,
20 or a switch, and receives an operation or an information input from a user. The
display device 910 includes a screen such as a liquid crystal display (LCD) and an
organic light-emitting diode (OLED) display, and displays an output image of the
smartphone 900. The spcaker 911 converts audio signals that are output from the
smartphone 900 to sounds.
25 [0149]
The radio communication interface 912 supports any cellular
communication scheme such as LTE and LTE-Advanced, and performs radio
communication. The radio comn~unicationin terface 912 may typically include, for
example, a BB processor 913 and an RF circuit 914. The BB processor 913 may
30 perform, for example, encodingldecoding, niodulating/demodulating, and
~nultiplexi~~gldemultiplexinagn,d performs various types of signal processing for
radio communication. Meanwhile, the RF circuit 914 may include, for example, a
mixcl; a filter, and an amplifier, and transmits and receives radio signals via the
antenua 916. The radio communication interface 912 may also be a one chip
inodulc that has the BB processor 913 aud the RF circuit 914 integrated thcreon.
5 The radio communication interface 912 may include the multiple BB processors 913
and the multiple RF circuits 914, as illustrated in FIG. 22. Although FIG. 22
illustrates the example in which the radio communication interface 912 includes the
multiple BB processors 913 and the multiple RF circuits 914, the radio
communication interface 912 may also include a single BB processor 913 or a single
10 RF circuit 914.
[Ol 501
Furthermore, in addition to a cellular con~munication scheme, the radio
communication interface 912 may support another type of radio communication
scheme such as a short-distance wireless communication scheme, a near field
15 communication scheme, and a radio local area network (LAN) scheme. In that case,
the radio communication interface 912 may include the BB processor 913 and the RF
circuit 914 for each radio communication scheme.
[0151]
Each of the antenna switches 915 switches connection destinations of the
20 antennas 916 among multiple circuits (such as circuits for different radio
communication schemes) included in the radio communication interface 912.
[0152]
Each of the antennas 916 includes a single or multiple antenna elements
(such as multiple antenna elements included in an MIMO antenna), and is used for
25 the radio communication interface 912 to transmit and rcceive radio signals. The
smartphone 900 nlay include the multiple antennas 916, as illustrated in FIG. 22.
Although FIG. 22 illustrates the example in which the smartphone 900 includes the
multiple antennas 916, the smartphone 900 may also include a single antenna 916.
[0153]
30 Fui-thermore, the smartphone 900 may include the antenna 916 for each
radio com~nunication scheme. In that case, the antenna switches 915 may be
omitted from the collfiguratioil of the smartphone 900.
[0154]
The bus 917 collnects the processor 901, the memory 902, the storage 903,
the external connection interface 904, the camera 906, the sensor 907, the
5 microphone 908, the input device 909, the display device 910, the speaker 911, the
radio communication interface 912, and the auxiliary controller 919 to each other.
The battery 918 supplies power to blocks of the smartphone 900 illustrated in FIG. 22
via feeder lines, which are partially shown as dashed lines in the figure. The
auxiliary controller 919 operates a minimum necessary function of the smartphone
10 900, for example, in a sleep mode.
[0155]
When the smartphone 900 illustrated in FIG. 22 operates as the small cell
base station 20, the communication control unit 242 and the mode setting unit 244 of
the small cell base station 20 may be implemented at the radio communication
15 interface 912. Further, at least part of these functions may he implemented at the
processor 901 or the auxiliary controller 919. Further, the smartphone 900 may be
utilized as the terminal apparatus 30.
[0156]
(Second Application Example)
20 FIG. 23 is a block diagram illustrating an example of a schematic
configuration of a car navigation apparatus 920 to which the technology of the
present disclosure may be applied. The car navigation apparatus 920 includes a
processor 921, a memory 922, a global positioning system (GPS) module 924, a
sensor 925, a data interface 926, a content player 927, a storage medium interface
25 928, an input device 929, a display device 930, a speaker 931, a radio
commu~lication interface 933, one or more antenna switches 936, one or more
antelmas 937, and a battery 938.
[0157]
The processor 921 may be, for example, a CPU or a SoC, and controls a
30 navigation function and another function of the car uavigation apparatus 920. The
memory 922 includes RAM aud ROM, and stores a program that is executed by the
processor 92 1, and data.
[0158]
The GPS module 924 uses GPS signals received from a GPS satellite to
measure a position (such as latitude, longitude, and altitude) of the car navigation
5 apparatus 920. The sensor 925 may include a group of sensors such as a gyro
sensor, a geomagnetic sensor, and an air pressure sensor. The data interface 926 is
connected to, for example, an in-vehicle network 941 via a terminal that is not shown,
and acquires data generated by the vehicle, such as vehicle speed data.
[0159]
10 he content player 927 reproduces content stored in a storage medium (such
as a CD and a DVD) that is inserted into the storage medium interface 928. The
input device 929 includes, for example, a touch sensor configured to detect touch
onto a screen of the display device 930, a button, or a switch, and receives an
operation or an information input from a user. The display device 930 includes a
15 screen such as a LCD or an OLED display, and displays an image of the navigation
function or content that is reproduced. The speaker 931 outputs sounds of the
navigation function or the content that is reproduced.
[0 1601
The radio communication interface 933 supports any cellular
20 communication scheme such as LET and LTE-Advanced, and performs radio
communication. The radio communication interface 933 may typically include, for
example, a BB processor 934 and an RF circuit 935. The BB processor 934 may
perform, for example, encoding/decoding, modulating/demodulating, and
~nultiplexing/demnltiplexing, and performs various types of signal processing for
25 radio communication. Meanwhile, the RF circuit 935 may include, for example, a
mixer. a filter, and an amplifier, and transmits and receives radio signals via the
antenna 937. The radio communication interface 933 may be a one chip module
having the BB processor 934 and the RF circuit 935 integrated thereon. The radio
communication interface 933 may include the multiple BB processors 934 and the
30 multiple RF circuits 935, as illustrated in FIG. 23. Although FIG. 23 illustrates the
example in which the radio communication interface 933 includes thc multiple BB
processors 934 and the multiple 1W circuits 935, the radio communication interface
933 may also include a single BB processor 934 or a single RF circuit 935.
[0161]
Furthermore, in addition to a cellular communication scheme, the radio
5 commu~~icatioinn terface 933 may support another type of radio comnlunication
scheme such as a short-distance wireless conlmunication scheme, a ncar field
communication scheme, and a radio LAN scl~eme. In that case, the radio
communication interface 933 may include the BB processor 934 and the RF circuit
935 for each radio communication scheme.
10 [0162]
Each of the antenna switches 936 switches connection destinations of the
antennas 937 among multiple circuits (such as circuits for different radio
communication schemes) included in the radio communication interface 933.
[0163]
15 Each of the antennas 937 includes a single or multiple antenna elements
(such as multiple antenna elements included in an MIMO antenna), and is used for
the radio communication interface 933 to transmit and receive radio signals. The
car navigation apparatus 920 may include the multiple antennas 937, as illustrated in
FIG. 23. Although FIG. 23 illustrates the example in which the car navigation
20 apparatus 920 includes the multiple antennas 937, the car navigation apparatus 920
may also include a single antenna 937.
[O 1641
Furthermore, the car navigation apparatus 920 may include the antenna 937
for each radio communication scheme. In that case, the antenna switches 936 may
25 be omitted from the configuration of the car navigation apparatus 920.
[0165]
The battery 938 supplies power to blocks of the car navigation apparatus
920 illustrated in FIG. 23 via feeder lines that are partially shown as dashed lines in
the figure. The battery 938 accumulates power supplicd form the vehicle.
30 LO1661
When the car navigation apparatus 920 illustrated in FIG. 23 operates as the
small cell base station 20, the conlmunication control unit 242 and the mode setting
unit 244 of the small cell base station 20 may be irnplelnented at the radio
communication interface 933. Further, at least part of these functions may be
implemented at the processor 921. Further, the car navigation apparatus 920 may
5 be utilized as the terminal apparatus 30.
[0167]
The technology of the present disclosure may also be realized as an invehicle
system (or a vehicle) 940 including one or more blocks of the car navigation
apparatus 920, the in-vehicle network 941, and a vehicle module 942. The vehicle
10 module 942 generates vehicle data such as vehicle speed, engine speed, and trouble
information, and outputs the generated data to the in-vehicle network 941.
[0168]
<6. Conclusion>
The embodiment of the technique according to the present disclosure has
15 been described in detail above using FIG. 1 to FIG. 23. According to the abovedescribed
embodiment, in a system in which a plurality of small cells are disposed,
each small cell is allocated to at least one of a plurality of small cell groups, and,
after the operation mode of each of the plurality of small cells is determined in units
of the small cell groups, a control message for specifying the operation modes in
20 units of the small cell groups is signaled to each small cell base station. Therefore,
also in an environment where a number of small cell base stations are deployed, it is
possible to avoid occurrence of a considerable signaling overhead for notification of
the operation modes of the small cells. Further, a small signaling overhead for
notification of the operation modes also means that it is allowed to increase
25 frequency of notifying the small cell base stations of the operation modes from the
control entities. Therefore, according to the technique according to the present
disclosure, it is possible to make the ratio of active small cells appropriately follow a
traffic state which temporally changes.
[0169]
30 By the way, it is also possible to employ a method in which a small base
station is activated on conditions that there is a te~minal in the vicinity of the small
cell base station. However, an existing positioning method such as a method based
on a global positioning system (GPS) or a method based on direction-of-arrival
estimation (DoA) does not have sufficient positioning accuracy compared to a cell
size of the small cell. Further, while there is larger needs for installation of the
6 small cell base station indoors than outdoors, the terminal existing indoors often
cannot utilize GPS positioning. Therefore, it is difficult to say that the operation
modes of the small cells based on positioning of the teiminal are effectively
controlled at the moment. On the other hand, with the technique according to the
present disclosure, the operation modes of the small cells are controlled in units of
10 the small cell groups according to the determination index relating to the system
capacity requirements for each of a relatively broad management area which can
correspond to the macro cell or the sector of the macro cell. Therefore, while
control is geographically rough to some extent, it is possible to variedly change the
ratio of active small cells so as to follow the traffic state. At that time, positioning
15 of the terniinals is not essential.
[0 1701
Note that the series of control processing by the respective apparatuses
described herein may be implemented by using any of software, hardware, and a
combination of software and hardware. Programs constituting the software are
20 previously stored in, for example, a recording medium (a non-transitory medium)
provided in the inside or the outside of the respective apparatuses. And the
respective programs are, for example, read into a random access memory (RAM)
during execution and executed by the processor such as the CPU.
[0171]
25 Furthel; the processes described using the flowcharts in the present
description may not necessarily be executed in the order indicated by the flowchai-t.
Some process steps may be executed in parallel. Further, additional process steps
may be en~ployeda, nd some process steps may be omitted.
[0 1721
30 The preferred embodilllent of the present disclosure has been described
above with reference to the accompanying drawings, whilst the present disclosure is
not li~nitcd to the above examples. A person skilled in the art may find various
alterations and modifications within the scope of the appended claims, and it should
be understood that they will naturally colne under the technical scope of the present
disclosure.
5 [0173]
In addition, the effects described in the present specification are merely
illustrative and demonstrative, and not limitative. In other words, the technology
according to the present disclosure can exhibit other effects that are evident to those
skilled in the art along with or instead of the effects based on the present
10 specification.
[0 1741
Additionally, the present technology may also be configured as below.
(1)
A cormnunication control apparatus including:
15 a communication unit configured to comrnunicate with each of
communication nodes operating a plurality of small cells, each of which belongs to at
least one of a plurality of small cell groups;
a determining unit configured to determine whether operation modes of the
plurality of small cells should be set to be an active mode in units of the small cell
20 groups; and
a signaling unit configured to signal a control message for specifying the
operation modes in units of the small cell groups, determined by the determining unit
to the communication nodes via the communication unit.
(2)
25 The communication control apparatus according to (I),
wherein each of the plurality of small cell groups includes small cells
disposed in a distributed manner over a management area corresponding to a macro
cell or a sector of the macro cell.
(3)
30 The colnnlunication control apparatus according to (2),
wherein the determining unit determines the operation modes in units of the
small cell groups using a detcrnlination index rclating to a system capacity
requirement.
(4)
The communication control apparatus according to (3),
wherein the determination index includes a traffic anlount actually occurring
in the management area.
(5)
The communication control apparatus according to (3),
wherein the determination index includes a traffic anlount predicted to occur
10 in the management area.
(6)
The communication control apparatus according to (5),
wherein the determining unit predicts the traffic amount based on a quality
of service (QoS) class of a terminal existing in the management area.
16 (7)
The communication control apparatus according to (2),
wherein the determination index includes the number of terminals existing
in the management area.
(8)
20 The communication control apparatus according to any one of (3) to (7),
wherein each small cell belongs to a single small cell group, and
wherein the determining unit determines that the operation modes of more
small cell groups should be set to be the active mode when the determination index
indicates a larger system capacity requirement.
25 (9)
The communication control apparatus according to any one of (3) to (7),
wherein the plurality of small cell groups include a different number of
small cells, and
wherein the determining unit determines that the operation mode of a s~nall
30 cell group including more small cclls should be set to be the active mode when the
determination index indicates a larger system capacity requirement.
(10)
The communication control apparatus according to any one of (3) to (9),
whercin the determining unit determines the operation modes in units of the
small cell groups using a table which maps a value of the determination index and
5 the operation mode for each of the small cell groups.
(11)
The communication control apparatus according to any one of (3) to (lo),
wherein the determining unit switches the determination index to be used
for determination of the operation modes according to a terminal handled within a
10 system or a type of trafiic.
(12)
The communication control apparatus according to (lo),
wherein the determining unit switches the table to be used for determination
of the operation modes according to a temporal condition.
15 (13)
The communication control apparatus according to any one of (1) to (12),
wherein the plurality of small cells include a dynamic cell dynamically
operated by a mobile terminal, and
wherein the determining unit determines that an operation mode of a first
20 small cell group to which the dynamic cell does not belong should be preferentially
set to be the active mode over a second small cell group to which the dynamic cell
belongs.
(14)
The communication control apparatus according to any one of (1) to (13),
25 wherein the signaling unit signals an allocation message indicating
allocation of the small cell groups to communication nodes operating the small cells
via the coinmunication unit upon initial registration of each small cell.
(15)
The comn~unicationc ontrol apparatus according to any one of (1) to (14),
30 wherein the plurality of small cells include a dynamic cell temporarily
operated by a iuobile terminal, and
wherein the mobile terminal determines allocation of the small cell groups
to the dynamic cell without requiring individual signaling from thc comn~unication
control apparatus.
(16)
5 The conlmunication control apparatus according to any one of (1) to (15),
wherein the communication unit broadcasts or multicasts the control
message to the plurality of communication nodes.
(1 7)
A comnlunication control method including:
grouping a plurality of small cells in a manner that each small cell belongs
to at least one of a plurality of sinall cell groups in a communication control
apparatus which communicates with each of communication nodes operating the
plurality of small cells;
determining whether operation modes of the plurality of small cells should
15 be set to be an active mode in units of the small cell groups; and
signaling a control message for specifying the determined operation modes
in units of the small cell groups to the communication nodes.
(18)
A radio communication apparatus including:
a radio communication unit configured to operate a first small cell among a
plurality of small cells, each of which belongs to at least one of a plurality of small
cell groups; and
a control unit configured to set an operation mode of the first small cell
according to a control message for specifying an operation mode determined for the
25 small cell group to which the first small cell belongs, the control message being
signaled fiom a control node which determines whether operation modes of the
plurality of small cells should be set to be an active mode in units of the snlall cell
groups.
(19)
30 A radio cornlnunication method including:
in a radio communication apparatus which operates a first small cell among
a plurality of small cells, each of which belongs to at least one of a plurality of small
cell groups, receiving a control message for specifying an operation mode
determined for a small cell goup to which the first small cell belongs, the control
message being signaled fiom a control node which determines whether operation
5 modes of the plurality of small cells should be set to be an active mode in units of the
small cell groups; and
setting the operation mode of the first small cell according to the received
control message.
(20)
10 A radio communication system including:
a corninunication control apparatus which includes
a plurality of cominunication nodes configured to operates a
plurality of small cells, each of which belongs to at least one of a plurality of small
cell groups,
15 a determining unit configured to determine whether operation
modes of the plurality of small cells should be set to be an active mode in units of the
small cell groups, and
a signaling unit configured to signal a control message for
specifying the operation modes in units of the small cell groups, determined by the
20 determining unit to the plurality of communication nodes.
Reference Signs List
radio communication system
macro cell base station
macro cell
communication control apparatus
radio communication unit
network comn~unicationu nit
storage unit
small cell data
operation mode table
control unit
comlllunication control unit
mode determining unit
signaling unit
small cell base station
small cell
radio conlmunication unit
network conlmunication unit
storage uGt
control unit
communication control unit
mode setting unit
terminal apparatus
CLAIMS
Claim 1
A cornrnunication control apparatus comprising:
a communication unit configured to communicate with each of
6 communication nodes operating a plurality of small cells, each of which belongs to at
least one of a plurality of small cell groups;
a determining unit configured to determine whether operation modes of the
plurality of sillall cells should be set to be an active mode in units of the small cell
groups; and
10 a signaling unit configured to signal a control message for specifying the
operation modes in units of the small cell groups, determined by the determining unit
to the communication nodes via the comlnunication unit.
Claim 2
15 The cornnlunication control apparatus according to claim 1,
wherein each of the plurality of small cell groups includcs small cells
disposed in a distributed manner over a management area corresponding to a macro
cell or a sector of the macro cell.
20 Claim 3
The communication control apparatus according to claim 2,
wherein the determining unit determines the operation modes in units of the
small cell groups using a determination index relating to a system capacity
requirement.
25
Claim 4
The coilununication control apparatus according to claim 3,
wherein the determination index includes a traffic amount actually occui~ing
in the managenlent area.
30
Claim 5
The com~nunicationc ontrol apparatus accordi~lgto claim 3,
wherein the determination index includes a traffic arnount predicted to occur
in the management area.
5 Claim 6
The com~nunicationc ontrol apparatus according to claim 5,
wherein the determining unit predicts the traffic arnount based on a quality
of service (QoS) class of a terminal existing in the management area.
10 Claim 7
The commu~licationc ontrol apparatus according to claim 3,
wherein the determination index includes the number of terminals existing
in the management area.
15 Claim 8
The communication control apparatus according to claim 3,
wherein each small cell belongs to a single small cell group, and
wherein the determining unit determines that the operation modes of more
small cell groups should be set to be the active mode when the determination index
20 indicates a larger system capacity requirement.
Claim 9
The communication control apparatus according to claim 3,
wherein the plurality of small cell groups include a different number of
25 small cells, and
wherein the determining unit detcrmines that the operation mode of a small
cell group including more small cells should be set to be the active mode when the
determination index indicates a larger system capacity requirement.
30 Claim 10
The con~inunicationc ontrol apparatus according to claim 3;
wherein thc determining unit determines the operation modes in units of the
small cell groups using a table which maps a value of the determination index and
thc operation mode for each of the small cell groups.
5 Claim ll
The cornmunicatio~c~on trol apparatus according to claim 3,
wherein the determining unit switches the determination index to be used
for determination of the operation modes according to a terminal handled within a
system or a type of traffic.
10
Claim 12
The communication control apparatus according to claim 10,
wherein the determining unit switches the table to be used for determination
of the operation modes according to a temporal condition.
15
Claim 13
The comn~unicationc ontrol apparatus according to claim 1,
wherein the plurality of small cells include a dynamic cell dynamically
operated by a mobile terminal, and
20 wherein the determining unit determines that an operation mode of a first
small cell group to which the dynamic ccll does not belong should be preferentially
set to be the active mode over a second small cell group to which the dynamic cell
belongs.
25 Claim 14
The communication control apparatus according to claim 1,
wherein the signaling unit signals an allocation message indicating
allocation of thc small cell groups to communication nodes operating the s~nalcl ells
via the communication unit upon initial registration of each small cell.
30
Claim 15
The communication control apparatus according to claim 1,
whcrein the plurality of small cclls include a dynamic cell ten~porarily
operated by a mobile terminal, and
wherein the mobile tcrminal determines allocation of the small cell groups
5 to the dynamic cell without requiring individual signaling fro111 the communication
control apparatus.
Claim 16
The communication control apparatus according to claim 1,
wherein the communication unit broadcasts or multicasts the control
message to the plurality of communication nodes.
Claim 17
A communication control method conlprising:
grouping a plurality of small cells in a manner that each small cell belongs
to at least one of a plurality of small cell groups in a communication control
apparatus which communicates with each of communication nodes operating the
plurality of small cells;
determining whether operation modes of the plurality of small cells should
20 be set to be an active mode in units of the small cell groups; and
signaling a control message for specifying the determined operation modes
in units of the small cell groups to the communication nodes.
Claim 18
25 A radio communication apparatus comprising:
a radio co~nmunication unit configured to operate a first small cell among a
plurality of small cells, cach of which belongs to at least one of a plurality of small
cell groups; and
a control unit configured to set an operation mode of the first small cell
30 according to a control message for specifying an operation nlode determined for the
small cell group to which the first small cell belongs, the control message being
signaled from a coiitrol node which deter~nincs whether operatioli modes of the
plurality of slnall cells should be set to be an active mode in units of the small cell
groups.
5 Claim 19
A radio coimu~ucationm ethod conll~rising: 8
in a radio communication apparatus which operates a first slnall cell among
a plnrality of small cells, each of wluclibelongs to at least one of a plurality of small
cell goups, receiving a co~ltrol message for specifying an operalio~l mode
10 deternlined for a small cell group to which the first small cell belongs, the colltrol
message being signaled from a co~itrol node which detei~nines whether operatioli
modes of the plurality of small cells should be set to be an active mode in units of the
small cell groups; and
setting the operation mode of the first slnall cell according to the received
15 coiltrol message.
Claim 20
A radio comnulucation system comprising:
a communication control appa~latusw hich includes
20 a plurality of conununicaiion nodcs configured to operates a
plurality of small cells, each of which belongs to at least one of a plurality of small
cell groups,
a determilung unit configured to detennine whether operation
modes of the plurality of small cells should be set to be an active mode in units of the
25 sinall ceii groups, and
a signaling unit configured to signal a control niessage for
specifyi~igth e operation modes in units of the small cell groups, determined by the
determining uni&,to the plurality of comnunicatioll nodes.